LIBRARY 


UNIVERSITY  OF  CALIFORNIA. 

Deceived 
^Accessions  No.*  ^ciazs  No. 


.*9  /  fl^J^ 


COMPOUND  LOCOMOTIVES 


ARTHUR  TANNATT  WOODS, 

M.  M.  E.  (CORNELL  UNIV.') 

LATE    ASSISTANT    ENGINEER    UNITED    STATES    NAVY  J     PROFESSOR    OF    MECHANICAL    ENGINEERING, 
UNIVERSITY  OF   ILLINOIS,   AND    PROFESSOR    OF   DYNAMIC     ENGINEERING,    WASHINGTON    UNI- 
VERSITY ;      MEMBER    OF    THE    AMERICAN     SOCIETY    OF     MECHANICAL     ENGINEERS; 
MEMBER   OF  THE   AMERICAN   SOCIETY   OF   NAVAL    ENGINEERS;   ASSOCIATE 
MEMBER    OF    THE    AMERICAN    RAILWAY    MASTER    MECHANICS 
ASSOCIATION,    ETC.,    ETC. 


SECOND  EDITION,   REVISED  AND  ENLARGED 


DAVID  LEONARD  BARNES,  A.M.,  C.  E. 

MEMBER   OF  THE   AMERICAN    SOCIETY   OF   CIVIL    ENGINEERS;     MEMBER   OF   THE   AMERICAN    SOCIETY 

OF     MECHANICAL     ENGINEERS;      ASSOCIATE     MEMBER     OF    THE     AMERICAN     RAILWAY 

MASTER    MECHANICS    ASSOCIATION;    ASSOCIATE    MEMBER    OF  THE    MASTER 

CAR    BUILDERS    ASSOCIATION,    ETC.,    ETC. 


CHICAGO 

THE  RAILWAY  AGE  AND  NORTHWESTERN  RAILROADER 

1893 


COPYRIGHT,  1889, 
ARTHUR  T.  WOODS. 


COPYRIGHT,  1893, 
HARRIET  DEK.  WOODS. 


STije  Hakest'Ue  $rea8 

R.  DONNELLEY   &  SONS  CO.,  CHICAGO 


PREFACE  TO  FIRST  EDITION. 


In  the  preparation  of  the  series  of  articles  which  are  here 
collected  in  book  form,  the  aim  of  the  author  was  to  combine 
the  description  of  the  various  forms  of  compound  locomotives 
which  have  been  actually  used,  with  so  much  of  the  theory  of 

the  design  of  compound  engines  as  would  seem  to  be  directly 

*  -    *  *  \ 
applicable  to  locomotive  pra'ctice. 

An  effort  has  been  made  to  present  an  unprejudiced 
analysis  of  each  type,  and  to  point  out  such  advantages  and 
disadvantages  as  are  apparently  clearly  demonstrable,  while 
carefully  avoiding  matters  of  individual  preference. 

Free  use  has  been  made  of  all  available  material,  and  the 
authority  for  data,  is  in  general  given  in  the  text.  The  author 
wishes  to  specially  acknowledge  his  indebtedness  to  Engineer- 
ing, and  to  Mr.  Anatole  Mallet,  civil  engineer,  Paris  ;  Mr.  A. 
von  Borries,  locomotive  superintendent  of  the  Hanover  Rail- 
road ;  Messrs.  Henry  and  Baudry,  of  the  Paris,  Lyons  & 
Mediterranean  Railway,  and  Mr.  G.  Du  Bousquet,  of  the 
Northern  Railway  of  France,  for  courteously  supplying  him 
with  information  concerning  their  designs. 

CHAMPAICN,  Illinois,  January,   1891. 


PREFACE   TO    SECOND    EDITION. 


In  the  preparation  of  the  second  edition  of  this  book  the 
aim  has  been  to  add  all  important  developments  since 
the  first  edition,  and  to  describe  not  so  much  the  plans  of 
various  inventors,  as  to  place  before  the  reader  the  actual 
construction  and  practical  value  of  compound  locomotives  that 
have  been  built  and  put  into  service,  and  to  that  end  proposed 
designs  have  been  omitted. 

Extended  theoretical  discussion  has  been  avoided  because 
of  the  'small  practical  value  of  such  analysis  with  the  limited 
data  from  actual  service  that  is  available  at  this  time. 

There  has  been  added  further  consideration  of  the  more 
important  functions  of  compound  locomotives,  based  on 
analyses  of  data  and  indicator  cards  which  were  not  available 
for  the  first  edition.  Especial  attention  has  been  given  to 
the  development  of  such  safe  conclusions  about  the  use  of  a 
compound  system  for  locomotives  as  are  indicated  by  the 
results  of  service. 

Technical  papers  have  been  drawn  upon  to  furnish  illus- 
trations for  the  second  edition,  and  as  it  has  been  found 
impracticable  to  refer  in  each  case  to  the  publication  from 
which  the  illustration  was  drawn,  occasion  is  now  taken  to 
acknowledge  the  valuable  assistance  thus  obtained  from  Amer- 
ican and  Foreign  publications. 

^The  first  ten  chapters  have  been  prepared  with  special 
reference  to  students.  Chapters  XI.  to  XX.  inclusive,  refer 
wore  particularly  to  the  different  types  of  compound  locomo- 


VI  PREFACE. 

tives,  and  have  been  arranged  for  designers  of  locomotives. 
Chapters  XXI.  to  XXIII.  inclusive,  are  intended  to  place 
before  the  reader  an  unprejudiced  comparison  of  the  different 
types,  and  to  indicate  why  double  expansion  is  expected  to 
be  more  economical  than  single  expansion  for  locomotives. 

The  Appendix  gives  further  information  about  the  topics 
treated  in  the  body  of  the  book,  and  is  intended  for  the 
purpose  of  illustration  and  explanation. 

Valuable  assistance  has  been  given  by  Mr.  E.  M.  Herr, 
formerly  Master  Mechanic  of  the  Chicago,  Milwaukee  &  St. 
Paul  Railroad,  and  Superintendent  of  the  Grant  Locomotive 

Works. 

DAVID  LEONARD  BARNES. 
CHICAGO,  September,  1893. 


TABLE  OF  CONTENTS. 


CHAPTER   I. 

ELEMENTARY    INDICATOR    CARDS. 

ARTICLE  PAGE 

1.  Types  of  Compound  Locomotives  Commonly  Used.  2 

2.  Receiver  Type  of  Elementary  Indicator  Cards.  2 

3.  Non-Receiver  Type   of  Elementary  Indicator  Card.         .         .         .         4 

CHAPTER    II. 

CLEARANCE,    COMPRESSION.    AND  CONSTRUCTION    OF    THE    EXPANSION 
CURVE. 

4.  Clearance.  9 

5.  Construction  of  the  Expansion  Curve. 10 

6.  Compression.  -         -         -         -'-II 

CHAPTER    III. 

MEAN    EFFECTIVE    PRESSURE. 

7.  Formula  for  Calculating  Mean  Effective  Pressure.    -         -         -  17 

8.  Difference  Between  Calculated  and  Actual  Mean  Effective  Pressure.        1 8 

9.  Decrease  of  Mean  Effective  Pressure  as  Speed  Increases.  19 

10.  Effect  on  Draw  Bar  Pull  of  Decrease  of  Mean  Effective  Pressure  as 

Speed  Increases.  19 

11.  Increase  of  Per  Cent,  of  Total  Power  Consumed  by  Locomotives  and 

Tenders   which  follows  a  Decrease   of  Mean   Effective   Pressure 
Due  to  Speed.  20 

CHAPTER    IV. 

DIFFERENCES    BETWEEN    ELEMENTARY    AND    ACTUAL    INDICATOR 
CARDS. 

12.  Difference  Between  Apparent  and  Actual  Cut-off.     -  25 

13.  Difference   Between  Actual   and  Elementary    Mean  Effective  Pres- 

sures in  High-Pressure  Cylinder.  26 

14.  Differences  Between  Actual  and  Elementary  Mean  Effective  Pres- 

sures in  Low- Pressure  Cylinder.  -------       29 


Vlll  TABLE    OF    CONTENTS. 

ARTICLE  PAGE 

15.  Differences  Between  Actual  Work  done  in  Cylinder  and  the  Work 

shown  by  Elementary  Indicator  Cards.    -  31 

16.  Indicator  Cards  in  Practice.  -       32 

17.  Drop  in  Pressure  During  Admission,  High-Pressure  Cylinder.  33 

1 8.  Rise  in  Pressure  During  Admission,  Low-Pressure  Cylinder.  33 

19.  Effect  of  Speed  on  Shape  of  Indicator  Cards.        -  35 

CHAPTER    V. 

EFFECT    OF    CHANGING    THE    POINT    OF    CUT-OFF — PRESSURE   IN 
THE    RECEIVER. 

20.  Effect  of  Changing  Cut-off  in  Elementary  Engine.  38 

21.  Effect  of  a  Change  of  Cut-off  on  the  Receiver  Pressure  in  an   Ele- 

mentary Engine.  40 

22.  Equalization  of  Work  in  the  High  and  Low-Pressure  Cylinders  of  a 

Receiver  Compound.  -  42 

23.  Equalization  of  Work  in  the  High  and  Low-Pressure  Cylinders  of  a 

Non-Receiver  Compound.  43 

24.  Conclusions  About  Equalization  of  Work  in  High  and  Low-Pressure 

Cylinders.  -         -  44 

25.  Pressure  in  the  Receiver.  44 

26.  Loss  Due  to  Drop  of  Pressure  in  Receiver.  47 

CHAPTER    VI. 

COMBINED    INDICATOR    CARDS    AND    WEIGHT    OF    STEAM    USED 
PER    STROKE. 

27.  Combined  Diagram,  Receiver  Type.                                      -         -  -       48 

28.  The  Rectangular  Hyperbola  as  a  Reference  Curve.  49 

29.  Location  of  Rectangular  Hyperbola  for  Reference.  51 

30.  Weight  of  Steam  Used  per  Stroke.  51 

31.  Weight  of  Steam  Retained  in  Cylinder  at  End  of  Compression.  52 

32.  Limitations  of  Combined  Diagrams.    -  53 

33.  Re-Evaporation  in  Receiver.    -  54 

34.  Condensation  in  Receiver.  -  54 

35.  What  is  Shown  by  Reference  Curve  on  Combined  Diagrams.    -  55 

36.  Ideal  Combined  Diagram.  -  55 

37.  Combined  Diagram  from  Non-Receiver  or  Woolf  Type.  -  57 

38.  Method  of  Combining  Indicator  Cards  from  Non- Receiver  Type.  58 

39.  Losses  Shown  by  Combined  Diagram  from  Non-Receiver  Type.  61 

40.  Correct  Area  of  Combined  Diagram,  Non-Receiver  Type.    -  63 

41.  Reference  Curve  for  Combined  Diagram,  Non-Receiver  Type.  63 

42.  Weight  of  Steam  per  Stroke.  64 

43.  Other  Reference  Curves  for  Combined  Diagrams.  65 

44.  Weight  of  Steam  per  Stroke,  Various  Compound  Locomotives.    -  6£ 


TABLE  OF  CONTENTS.  IX 

CHAPTER,  VII. 

TOTAL   EXPANSION.      RATIO    OF    CYLINDERS. 


ARTICLE 


PAGE 


45.  Total  Expansion  from  Elementary  Indicator  Cards.  -  69 

46.  Total  Expansion  from  Actual  Indicator  Cards.  69 

47.  Ratio  of  Cylinders,  Elementary  Formulas  for.  72 

48.  Ratio  of  Cylinders  as  Affected  by  Maximum  Width  of  Locomotive.  72 

49.  Ratios  of  Cylinders  Commonly  Used.  73 

50.  Ratio  of  Cylinders    as    Affecting   Equalization    of   Power  in  Two- 

Cylinder  Receiver  Compounds.  74 

51.  Ratio   of  Cylinders   and    Equalization    of  Power    in   Non-Receiver 

Compounds.       -  '-75 

52.  Ratio  of  Cylinder  Volumes  to  the  Work  to  be  Done.  76 

t 

CHAPTER   VIII. 

RECEIVER    CAPACITY,    RE-HEATING  AND    SEQUENCE    OF    CRANKS. 

53.  Receiver  Capacity.  80 

54.  Re-Heating  and  Steam  Jackets.  -                                                                     80 

55.  Smoke  Box  Temperatures.  82 

56.  Sequence  of  Cranks.  -  83 

CHAPTER    IX. 

MAXIMUM    STARTING    POWER    OF    LOCOMOTIVES. 

57.  Starting  with  Close  Coupled  Cars  and  with  Free  Slack.    -  84 

58.  Starting  of   Two-Cylinder   Receiver  Compounds  Without  an   Inde- 

pendent Exhaust  for  the  High-Pressure  Cylinder.  84 

59.  Starting  of  Two-Cylinder  Receiver   Compounds  with  Independent 

Exhaust  for  High-Pressure  Cylinder.    -  85 

60.  Starting  of  Four-Cylinder  Two-Crank    Receiver   and   Non-Receiver 

Compounds.    -  85 

61.  Starting  of  Four-Cylinder  Four-Crank  Compounds  with  Receivers.  -  86 

62.  Starting  and  Hauling  Power  of  Single  Expansion  Locomotives.  -  86 

63.  Graphical  Representation  of  Hauling  Power.  -  87 

64.  Starting    Power   with    Mallet's    System    and    other    Non-Automatic 

Starting  Gears.  90 

65.  Starting    Power  with  Worsdell,  von  Berries    and  other   Automatic 

Starting  Gears.    -  91 

66.  Starting  Power  with  the  Lindner  system.      -•  94 

67.  Starting  Power  of  Three-Cylinder  Three-Crank  Compounds.    -  95 

68.  Variation  of  Hauling  Power  with  Four-Cylinder  Two-Crank  Receiver 

and  Non-Receiver  Compounds. 95 


X  TABLE    OF    CONTENTS. 

CHAPTER    X. 

CONDENSATION    IN    CYLINDERS. 

ARTICLE  PAGE 

69.  Range  of  Temperature.  -  -       97 

70.  Need  of  Covering  Hot  Surfaces  to  Prevent  Radiation.  97 

71.  Condensation,  Leakage  of  Valves  and  Re-Evaporation  as  Determined 

from  Indicator  Cards.  -          -          -       98 

72.  Examples   of  Determination   of   Condensation,    Leakage,    and    Re- 

Evaporation  from  Various  Indicator  Cards.  -         -         -          102 

CHAPTER   XL 

THE    VALVE    GEAR    ADJUSTMENTS. 

73.  Mallet's  System  of  Cut-Off  Adjustment.  -         -         -  106 

74.  Chicago,  Burlington  &  Quincy  System.  108 

75.  Heintzelman  System.  .....          -  109 

76.  The  Rogers  Locomotive  Works  Link  Hanger  Adjustment.  -         -  m 
760.  Different   Adjustments   of  Cut-Offs  that    have  been  Used  for  Com- 

pound Locomotives.     -  ••---III 

CHAPTER    XII. 

MAIN    VALVES. 

77.  Lap,  Travel,  and  Size  of  Ports.  -         .         -  122 

78.  Piston  Valves.  ------....  I22 

79.  Some  Effects  of  Inadequate  Valve  Motions.  -         -         -  123 

80.  Effect  of  Long  Valve  Travel  and  Inside  Clearance  or  Negative  Lap.  124 

81.  Conclusions  about  Main  Valve  Dimensions.  jo 


CHAPTER    XIII. 

STEAM    PASSAGES  —  ACTION    OF    EXHAUST. 

82.  Size  of  Steam  Passages  and  Loss  Due  to  Wire-Drawing.  -         -     132 

83.  Effect  of  Exhaust  on  Fire  and  on  Back  Pressure.         -         -         -          135 

CHAPTER    XIV. 

EFFECT    OF    HEAVY    RECIPROCATING    PARTS. 

84.  Weight  of  Reciprocating  Parts.        -  -         -         -         -  139 

85.  Advantage  of  Large  Drivers.  I40 

86.  Counterbalancing  of  Reciprocating  Parts.  -         -          -  140 

87.  Marine  Practice  in  Counterbalancing.  -  140 

88.  Effect  of  Decreasing  Weight  of  Reciprocating  Parts  and  Increasing 

Diameter  of  Drivers.  -         .          -      144 

89.  Distribution  of   Centrifugal    Tendency  of  Counterbalance  over   the 

Track.    -  I44 


TABLE  OF  CONTENTS.  XI 

CHAPTER  XV. 

DESCRIPTION  OF  TWO-CYLINDER  RECEIVER  COMPOUNDS,  WITH  AUTO- 
MATIC INTERCEPTING  VALVE  STARTING  GEARS,  AND  WITHOUT 
SEPARATE  EXHAUST  FOR  HIGH-PRESSURE  CYLINDER  AT  STARTING. 

ARTICLE  PAGE 

90.  The  von  Borries  System  in  1889.  147 

91.  The  von  Borries  System  as  used  on  the  Jura,  Berne-Lucerne  Railway.     150 

92.  A  Modification  of  the  von  Borries  System.  -  151 

93.  Recent  Changes  in  the  von  Borries  System.  153 

94.  The  Worsdell  System.  153 

95.  A  Modification  of  the  Worsdell  System.  -  155 

96.  The  Schenectady  Locomotive  Works  (Pitkin)  System.  157 

97.  A    Modification  of    the   Schenectady    Locomotive    Works  (Pitkin) 

System.  160 

98.  The  Dean  System.       -  165 

99.  A  Modification  of  the  Dean  System.  165 

100.  The  Brooks  Locomotive  Works  (Player)  System.  169 

10 1.  The  Rogers  Locomotive  Works  System.  -  171 

102.  The  Baldwin  Locomotive  Works  System.  178 

CHAPTER    XVI. 

DESCRIPTION  OF  TWO-CYLINDER  RECEIVER  COMPOUNDS,  WITH  AUTO- 
MATIC STARTING  GEAR  AND  WITHOUT  SEPARATE  EXHAUST  FOR 
HIGH-PRESSURE  CYLINDER  AT  STARTING,  AND  WITHOUT  INTER- 
CEPTING VALVE.  THE  LINDNER  SYSTEM;  THE  COOKE  LOCOMOTIVE 
WORKS  SYSTEM;  THE  GOLSDORF  (AUSTRIAN)  SYSTEM. 

103.  The  Lindner  System.  181 

104.  A  Modification  of  the  Lindner  System.  184 

105.  The   Lindner  System  as  Used  on  the  Saxon  State  Railroad;  The 

Meyer-Lindner  Duplex  Compound.  185 

1 06.  The  Lindner  System  on  the  Chicago,  Burlington  &  Quincy  Railroad.  185 

107.  The  Lindner  System  on  the  Pennsylvania  Railroad.  -         -         -  1 88 

108.  The  Cooke  Locomotive  Works  System.  192 

109.  The  Golsdorf  (Austrian)  System.      -         -         -  194 

CHAPTER   XVII. 

DESCRIPTION  OF  TWO-CYLINDER  RECEIVER  COMPOUNDS,  WITH  INTER- 
CEPTING VALVE,  AND  WITH  SEPARATE  EXHAUST  FOR  HIGH-PRES- 
SURE CYLINDER  AT  STARTING. 

1 10.  The  Mallet  System.  -     196 
in.  The  Early  Form  of  the  Mallet  System.  199 

112.  Preliminary  Work  of  Mallet.    -  201 

113.  Rhode  Island  Locomotive  Works  (Batchellor)  System.  -         -          202 


Xll       .  TABLE    OF    CONTENTS. 

ARTICLE  PAGE 

114.  The  Richmond  Locomotive  Works  (Mellin)  %stem.  205 

115.  The  Pittsburgh  Locomotive  Works  (Colvin)  System.  -         208 

1 1 6.  von  Berries'  Latest  System.  -  209 

CHAPTER    XVIII. 

DESCRIPTION  OF  FOUR-CYLINDER    NON-RECEIVER    COMPOUNDS,  "CONTIN- 
UOUS"   EXPANSION    OR    WOOLF  TYPE,  VAUCLAIN  AND    NON-RECEIVER 
•     TANDEM   TYPES. 

117.  The  Dunbar  System.  21 1 

118.  The    Du  Bousquet   (Woolf)    System  on   the    Northern    Railway    of 

France.  211 

119.  Indicator  Cards  from  the  Du  Bousquet  (Woolf)  Compound.  213 

120.  Baldwin  Locomotive  Works  (Vauclain)  System.  215 

121.  Distribution  of  Pressure  on  Pistons.          -  228 

122.  Advantages  Claimed  for  the  Baldwin   Locomotive  Works  (Vauclain) 

System.  -         -  232 

123.  The  Johnstone  System  on  the  Mexican  Central  Railway.  233 

CHAPTER    XIX. 

DESCRIPTION    OF    FOUR-CYLINDER,    TWO-CRANK    RECEIVER     COM- 
POUNDS— TANDEM    RECEIVER    TYPES. 

124.  Tandem  Compounds  on  the  Hungarian  State  Railway.  235 

125.  Tandem  Compounds  on  the  Southwestern  Railways  of  Russia.  237 

126.  Indicator   Cards    from  Tandem    Compounds    on    the    Southwestern 

Railways  of  Russia.  .....  238 

127.  The  Brooks  Tandem  System.  -    .  -         -  239 

CHAPTER    XX. 

DESCRIPTION    OF    THREE    AND    FOUR-CRANK    COMPOUNDS. 

128.  Webb  System;  Express  Locomotives  without  Parallel  Rods.  244 

129.  Webb  System;  Freight  Locomotives  with  Parallel  Rods.  245 

130.  Webb  System  on  Pennsylvania  Railroad.  245 

131.  Three-Cylinder  System  Used  on  the  Northern  Railways  of  France.  246 

132.  Valve  Gear  for  Three-Cylinder  Compound  on  Northern  Railways  of 

France.        -  247 

133.  Summary  of  Three  and  Four-Crank  Compounds.  248 

134.  Miscellaneous  Designs    of  Compounds    that  have  Not  been   Put  in 

Service.       -         -  248 

CHAPTER    XXI. 

SUMMARY    ABOUT    STARTING    GEARS. 

135.  Automatic  Starting  Gears  with  Intercepting  Valves.         -         -         -     249 


TABLE    OF    CONTENTS.  Xlll 

ARTICLE  PAGE 

136.  Automatic  Starting  Gears  Without  Intercepting  Valves.      -  251 

137.  Non-Automatic  Gears  With  Intercepting  Valves  and  With  Separate 

Exhausts  for  the  High-Pressure  Cylinders.   -         -         -         -  251 

138.  Starting  Gears  for  Four-Cylinder  Compounds.      ....  252 

CHAPTER    XXII. 

REASONS    FOR    ECONOMY    IN     COMPOUND    LOCOMOTIVES. 

139.  Possibilities  of  Savings.  254 

140.  Saving  by  Greater  Expansion. 255 

141.  Saving  by  Reduction  of  Condensation.    -  256 

142.  Saving  by  more  Complete  Combustion.  256 

143.  Saving  in  Fast  Express  and  Passenger  Service.  257 

144.  Saving  in  Slow  Grade  Work  and  in  Freight  and  Suburban  Service.  257 

145.  How  Saving  is  Affected  by  the  Price  of  Fuel  and  Rate  of  Combustion.  258 

146.  Cost  of  Repairs.  262 

147.  Methods  of  Operating  to  Gain  Economy.    -  264 

CHAPTER    XXIII. 

SELECTION    OF    TYPE    AND    DETAILS    OF    DESIGN    BEST    ADAPTED    FOR  A 
GIVEN    SERVICE. 

148.  Four-Cylinder  Four-Crank  Types. :  269 

149.  Three-Cylinder  Three-Crank  Types.    -  270 

150.  Four-Cylinder  Tandem  Two-Crank  Types.       -         -  270 

151.  Four-Cylinder  Non-Tandem  Two -Crank  Types,  With  and  Without 

Receivers.                  -         -         -         -  272 

152.  Two-Cylinder  Two-Crank  Receiver  Types.  275 

153.  In  General  About  a  Selection  of  a  Suitable  Design.     -         -         -  277 


APPENDIX. 

A.  Example    of  Calculation    for   Mean    Effective    Pressure    during   One 

Stroke.  281 

B.  Example  of  Calculation  for  Mean  Effective  Pressure  during  Expansion.  281 

C.  Example  of  Calculation  for  Pressure  in  the  Receiver.  281 

D.  Final  Pressure  ;  Total  Expansion.  281 

E.  Drop  in  Pressure  in  Receiver.  282 

F.  Mean  Effective  Pressure  ;  Equivalent  in  One  Cylinder.  282 

G.  Example  of  Calculation  for  Mean  Effective  Pressure  when  Clearance 

is  taken  into  Account.  ......  283 

H.  Derivation  of  Formula  for  Tractive  Force.  283 

I..    Some  further  Discussion  of  Three-Cylinder,  Three-Crank  Compounds.  284 


XIV  TABLE    OF    CONTENTS. 

PAGE 

J.  Example  of  Modification  of  Elementary  Indicator  Cards  to  Approxi- 
mate to  Actual  Cards  for  Non-Receiver  Compounds.  292 

K.  Some  Further  Discussion  of  Four-Cylinder  Receiver  Compounds.  293 

L.  Diagram  of  Turning  Moments  of  a  Lindner  Two-Cylinder  Receiver 

Compound.  299 

M.  Some  Tests  of  Compound  Locomotives  in  the  United  States.     (Table 

II.)  30i 
N.  Reported  Savings  of  Compound  Locomotives  in  the  United  States. 

(Table  H  H.)  302 

O.  Formulas  for  Expansion  Curve. 303 

P.  Formula  for  Inertia  of  Reciprocating  Parts.  303 
Q.  Comparative  Cylinder  Capacities  of  Compound  Locomotives. 

(Table  L.)  305 
R.  Dimensions  of  Some  of  the  more  Prominent  Compound  Locomotives 

that  have  been  Put  into  Actual  Service,  Chiefly  in  the  United  States. 

(Table  C  C.)  307 

Glossary. 311 

Index. -  ....  1 


COMPOUND    LOCOMOTIVES. 

CHAPTER  I. 

ELEMENTARY  INDICATOR  CARDS. 

The  elementary  theory  of  steam  use  in  compound 
locomotives  does  not  differ  from  that  of  other  compound 
non-condensing  engines,  but  it  has  been  found  that  some 
factors,  which  are  of  comparatively  small  consequence  in 
marine  or  stationary  work,  become  of  importance  in  the 
locomotive.  This  arises  largely  from  the  wide  range  of 
power  required  from  locomotives,  and  the  practical  neces- 
sity of  keeping  the  valve  gear  and  operating  mechanism  as 
free  from  complication  as  possible.  The  recent  introduction 
of  higher  pressures  and  greater  piston  speeds  in  marine 
practice  has  made  some  of  the  working  conditions  of  marine 
engines  more  nearly  like  the  conditions  of  locomotive  use 
than  they  have  been  heretofore. 

The  action  of  steam  in  expanding  in  a  slow  moving, 
elementary  compound  engine  is  well  laid  down  in  text 
books,  and  the  elementary  indicator  cards  show  in  a  general 
way  how  steam  acts  in  an  engine.  This  is  well  understood 
by  most  of  those  who  will  be  called  upon  to  design  the  cyl- 
inders and  valve  motion  of  compound  locomotives.  Such 
elementary  analysis  is,  however,  of  but  little  value  as  a 
guide  to  an  understanding  of  what  takes  place  in  a  com- 
pound locomotive.  This  results  mainly  from  the  high  piston 
speed  which  causes  excessive  wire-drawing  and  compression 
with  the  valve  motions  ordinarily  used.  Such  motions  are 
universally  positive  and  direct,  and  do  not  differ  materially 


2  COMPOUND     LOCOMOTIVES. 

in  action  from  the  well-known  Stephenson  link,  and  have, 
generally  speaking,  all  of  its  defects.  Although  elemen- 
tary analysis  has  a  limited  application  to  the  compound 
locomotive,  yet  it  is,  perhaps,  best  to  review  the  elementary 
theory  somewhat  in  order  to  properly  introduce  the  more 
complicated  and  involved  conditions,  which  actually  exist 
in  a  practical  engine. 

1.  Types    of    Compound    Locomotives    Commonly 
Used. — There  are  two  distinct  types  of  compound  engines 
that  have  been  commonly  used  ;  one  has  a  large  receiver 
between  the  cylinders,  into  which  the  h.  p.  cylinder  exhausts, 
and  from  which  the   1.  p.  cylinder  takes  steam.     The  other 
form  has  no  receiver,  so-called,  but  may  have  a  small  space 
between    the  cylinders,    consisting  of    the   volume   of    the 
clearances  of  the  cylinders  and  the  volume  of  the  space  in 
the  valve. 

The  first  type  of  compound  is  commonly  called  the 
"  receiver  "  type  ;  the  second,  without  a  receiver,  is  gener- 
ally known  as  the  "Woolf"  or  "continuous  expansion" 
type,  and  is  only  used  for  locomotives,  in  which  both  pistons 
are  attached  to  the  same  crosshead.  The  Woolf  type  of 
expansion  of  steam  is  used  in  the  Vauclain  type,  built  by 
the  Baldwin  Locomotive  Works,  and  the  Johnstone  type, 
used  on  the  Mexican  Central  Railway. 

2.  Receiver  Type  of  Elementary  Indicator  Cards. — 
The  combined  elementary  indicator   card  from   a   receiver 
compound  engine  has  the  general  form  shown  by  Fig.  I  when 
no  account  is  taken  of  the  clearance  spaces,  and  when  it  is 
assumed  that  steam  is  admitted   and   exhausted  exactly  at 
the  beginning  and   end  of   the   stroke,  and  no  allowance  is 
made  for  wire-drawing  through   the   steam  ports,  for  com- 
pression,  nor   for  irregularity   caused  by  the  angularity  of 
the  connecting  rods. 

The  upper  part  of  the  card,  a,  b,  c,  d,  e,f,  a,  is  from  the 
h.  p.  cylinder,  and  the  lower  part  of  the  card,  e,  /,  g,  h,  k,  e, 


ELEMENTARY    INDICATOR    CARDS.  3 

is  from  the  1.  p.  cylinder.  The  cards  are  on  the  same  scale 
of  pressures  and  have  the  same  length,  and  are  placed  with 
respect  to  each  other  as  they  would  be  when  the  cranks  are 
placed  at  right  angles.  This  appears  from  the  fact  that 
the  point  e,  the  admission  to  the  1.  p.  cylinder,  is  placed  in 
the  middle  of  the  card  from  the  h.  p.  cylinder,  or  just  one- 
half  a  stroke  later  than  the  admission  point  a  to  the  h.  p. 
cylinder.  The  h.  p.  card  leads  to  the  right  and  the  1.  p.  to 
the  left,  as  a  matter  of  convenience  in  illustration,  as  will 
appear  later. 


ZERO  LINE  OF  PRESSURE 


FIG.  i. 
Receiver  Type  of  Elementary  Indicator  Card. 

The  following  is  a  description  of  the  different  lines  on 
this  combined  diagram :  At  a  steam  is  admitted  to  the 
h.  p.  cylinder  with  a  pressure  corresponding  to  the  distance 
of  a  above  the  atmospheric  line.  Steam  continues  to  be 
admitted  at  this  pressure  until  the  piston  has  advanced  to 
the  cut-off  point,  at  half-stroke  in  this  case,  b.  From  b  to 
c  steam  expands,  and  at  c  is  exhausted  into  the  receiver. 
The  fall  in  pressure  from  c  to  d  represents  the  drop  of 
pressure  into  the  receiver,  and  is  a  source  of  loss  in  com- 
pound engines,  26.  The  most  perfect  compounds  have  no 
drop  of  any  magnitude  when  the  h.  p.  cylinder  opens  to 
the  receiver,  36.  From  d  to  e  the  h.  p.  piston  is  pushing  steam 
into  the  receiver.  At  e  steam  is  admitted  to  the  1.  p. 


4  '  COMPOUND    LOCOMOTIVES. 

cylinder  from  the  receiver,  and  from  e  to /steam  is  being 
pushed  into  the  receiver  from  the  h.  p.  cylinder,  and  is 
being  taken  out  of  the  receiver  by  the  1.  p.  cylinder. 

The  drop  in  pressure  from  e  to  /is  the  fall  of  pressure 
in  the  receiver,  and  results  from  the  fact  that  the  1.  p. 
cylinder  takes  more  steam  out  of  the  receiver  from  e  to  / 
than  is  put  into  it  by  the  h.  p.  piston  during  the  same  time. 
At /the  h.  p.  piston  ceases  to  push  steam  into  the  receiver, 
it  being  at  the  end  of  the  stroke.  At  this  point  also,  for 
the  purpose  of  illustration,  it  has  been  assumed  that  the 
1.  p.  valve  cuts  off  the  steam  from  the  receiver;  therefore, 
from/to  g  steam  is  expanding  in  the  1.  p.  cylinder.  The 
fall  from  g  to  h  shows  the  drop  in  pressure  at  the  exhaust 
of  the  1.  p.  cylinder  to  the  atmosphere.  From  h  to  k  is  the 
line  of  back  pressure  in  the  1.  p.  cylinder,  which  is  some- 
what above  the  atmospheric  line,  as  shown. 

In  all  practical  engines,  or  nearly  all,  the  cylinders  are 
double  acting,  and  therefore,  in  the  engine  assumed  for 
Fig.  I,  there  will  be  an  exhaust  of  steam  at  the  end  of  each 
stroke  of  the  h.  p.  piston  ;  hence,  when  the  1.  p.  piston  has 
moved  to  the  point /from  e,  there  will  be  at  /an  increase 
of  pressure  in  the  receiver  and  in  the  1.  p.  cylinder,  due  to 
the  exhaust  from  the  opposite  end  of  the  h.  p.  cylinder, 
which  will  cause  in  actual  work  the  point /to  rise  slightly. 
This  will  appear  from  an  examination  of  an  actual  indicator 
card.  See  Fig.  14.  A  different  arrangement  of  the  cut-off 
from  that  assumed  for  Fig.  I  would  cause  a  somewhat 
different  shape  of  combined  card,  but  in  general  the 
description  given  will  answer  for  all  elementary  indicator 
cards  from  receiver  compounds. 

3.  Non-Receiver  Type  of  Elementary  Indicator 
Card. — In  locomotive  practice,  so  far,  four-cylinder  com- 
pounds without  receivers  are  so  made  that  the  h.  p.  and  1.  p. 
pistons  move  together.  This  type  includes  the  Du  Bousquet 
non-receiver  tandem,  the  Vauclain,  and  the  Johnstone, 


ELEMENTARY    INDICATOR    CARDS.  5 

of  the  types  that  have  been  put  into  practical  service,  and 
others  that  have  been  suggested  but  not  built.  The  prob- 
lems to  be  solved,  when  the  pistons  move  simultaneously 
are,  in  some  respects,  quite  different  from  those  for  receiver 
engines. 

The  Woolf,  or  "  continuous  expansion  "  engines,  is  typ- 
ical of   this   class ;  the  pistons   move   simultaneously    and 


FIG.  2. 
Non-Receiver  Type  of  Elementary  Indicator  Card. 

there  is  no  receiver.  In  the  simplest  forms  of  this  type,  as 
applicable  to  locomotives,  the  h.  p.  and  1.  p.  pistons  are 
attached  to  the  same  crosshead,  and  the  slide  valves  of 
both  cylinders  are  operated  by  the  same  link  motion.  The 
peculiarities  of  the  steam  distribution  in  this  arrangement 
of  cylinders  can  be  best  examined  by  means  of  elementary 
indicator  cards  such  as  Fig.  2. 

Referring  to  this  figure,  a,  b,  d,  e,  /,  g,  h,  k,  a  is  the 
h.  p.  card,  and  g,  h,  /,  m,  n,  q,  g  is  the  1.  p.  card.  In  the 
h.  p.  cylinder  cut-off  takes  place  at  b,  and  there  is  expansion 
in  that  cylinder  until  the  exhaust  opens  at  d.  There  is 


6  COMPOUND    LOCOMOTIVES. 

then  a  drop  in  pressure  to  e  as  the  steam  in  the  h.  p.  cyl- 
inder mingles  with  that  in  the  passages  which  connect 
the  cylinders.  From  e  to  f  there  is  further  expansion  in 
the  h.  p.  cylinder  and  the  connecting  passages.  At  /  the 
1.  p.  steam  valve  opens  and  there  is  another  drop  in 
pressure  to  g. 

From  g to  h  the  cylinders  are  in  communication,  and  there 
is  expansion  until  the  1.  p.  steam  valve  closes  at  h.  From 
h  to  k  there  is  compression  in  the  connecting  passages  and 
the  h.  p.  cylinder,  and  when  the  h.  p.  exhaust  closes  at  k 
there  is  further  compression  in  that  cylinder.  In  the  1.  p. 
cylinder  the  steam  expands  from  h  to  /,  where  release 
occurs  and  the  pressure  drops  to  the  ordinary  back 
pressure  line. 

The  fall  of  pressure  in  the  1.  p.  cylinder  up  to  cut-off  is 
shown  by  g  h.  The  pressure  falls  because  the  amount  of 
steam  pushed  into  the  1.  p.  cylinder  by  the  h.  p.  piston  is  less 
than  the  volume  displaced  by  the  1.  p.  piston  in  the  same 
time.  At  the  point  h  the  1.  p.  cylinder  cuts  off  and  com- 
munication is  closed  between  the  h.  p.  and  1.  p.  cylinders  ; 
hence,  from  h  to  a  the  steam  remaining  in  the  h.  p.  cylin- 
der is  compressed,  for  it  has  no  outlet.  This  is  often  called 
"continuous  expansion,"  as  there  is  no  pause  of  expansion 
as  in  the  case  of  those  engines  where  the  steam  is  passed  to 
an  intermediate  receiver  after  expansion  in  one  cylinder. 

The  features  of  this  diagram  which  require  special 
attention  are  the  losses  in  pressure  at  d  and  /"and  the  com- 
pression in  the  h.  p.  cylinder.  In  order  to  prevent  the 
drop  at  d,  either  the  pressure  in  the  connecting  passages, 
valves  and  clearance  spaces  between  the  cylinders  when  the 
h.  p.  exhaust  opens  must  be  the  same  as  that  at  d,  or  else 
the  volume  of  the  connecting  passages  must  be  practically 
nothing.  The  pressure  can  possibly  be  made  the  same  as 
at  d  by  adjustments  of  the  1.  p.  cut-off,  but  it  is  not  prac- 
ticable on  account  of  the  unavoidable  complications.  The 


ELEMENTARY    INDICATOR    CARDS.  7 

only  feasible  method  of  reducing  this  loss  to  an  inapprecia- 
ble amount  appears  to  be  to  make  the  volume  of  the 
connecting  passages  very  small  compared  with  that  of  the 
h.  p.  cylinder.  The  drop  in  pressure  at /can  be  prevented 
or  reduced  by  compressing  to  the  pressure  /  in  the  1.  p. 
cylinder,  or  by  making  the  1.  p.  clearance  very  small. 

The  question  of  compression  in  the  h.  p.  cylinder  in  this 
type  of  engine  is  even  more  troublesome  than  in  receiver 
engines.  In  order  to  avoid  compressing  to  a  higher  pres- 
sure than  the  initial  pressure  with  the  usual  forms  of  valve 
gear,  it  is  necessary  that  the  volume  of  the  h.  p.  clearance 
space  should  be  made  large,  since  the  pressure  at  k,  where 
the  compression  caused  by  the  exhaust  closure  begins,  is  una- 
voidably high.  This  pressure  can,  of  course,  be  somewhat 
reduced  by  making  the  volume  of  the  passages  connecting 
the  cylinders  large,  but,  as  has  been  shown,  this  involves  a 
considerable  drop  in  pressure  at  d,  37.  See  Figs,  n,  12 
and  I  50. 

The  expedient  of  giving  the  h.  p.  valve  inside  clearance 
may  also  be  employed  in  connection  with  a  large  clearance 
space  to  assist  in  keeping  down  the  compression.  In  any 
case  in  which  the  shifting  link  motion  is  used,  early  cut- 
offs are  to  be  avoided,  both  on  account  of  this  compression 
and  to  avoid  the  wire-drawing  which  results  from  a  small 
port  opening.  The  use  of  late  cut-offs  has  been  advocated 
by  the  builders  of  this  class  of  engine  for  the  reason  just 
given,  but  that  involves  the  wire-drawing  of  the  steam  for 
all  light  work  by  closing  the  throttle.  This  leads  to  loss  of 
potential  of  pressure  and  is  not  conducive  to  economy, 
especially  in  compound  engines,  as  has  been  shown  by  Pro- 
fessor Goss  in  the  Purdue  University  shop  tests.  See 
Fig.  45.  80,  151. 

It  is,  however,  not  necessary  to  resort  to  very  early  cut- 
offs in  order  to  obtain  a  sufficiently  great  expansion,  as  this 
may  be  secured  by  using  a  comparatively  large  cylinder 


8  COMPOUND    LOCOMOTIVES. 

ratio,  but  at  high  speeds  the  wire-drawing  and  compression 
modifies  this  greatly,  77-82. 

In  determining  the  proportions  for  the  valve  gear  and 
the  size  of  the  cylinders  advisable  for  a  tandem  compound 
which  is  intended  to  take  the  place  of  single  expansion 
locomotive,  the  most  satisfactory  mode  of  procedure  will  be 
to  take  actual  cards  from  similar  engines  for  various  points 
of  cut-off,  measure  the  area  of  these  cards,  and  finally  to 
adjust  these  cards  for  losses  or  gains,  according  to  any  pro- 
posed changes  in  design  or  method  of  operation.  An  exam- 
ple of  .estimating  from  elementary  indicator  cards  is  given 
in  Appendix  J, 


CHAPTER  II. 

CLEARANCE,  COMPRESSION,  AND  CONSTRUCTION  OF  THE 
EXPANSION  CURVE. 

4.  Clearance. — The  volume  included  between  the  pis- 
ton, when  at  the  end  of  a  stroke,  and  the  valve  face  at  that 
end  is  called  the  "  clearance."  It  includes  the  volume  of  the 
steam  port,  the  space  'between  the  piston  and  the  cylinder 
head,  and  any  other  spaces  that  are  in  communication  with 

\b 


FIG.  3. 
Construction  of  Expansion  Curve. 

these  spaces,  such  as  indicator  pipes  and  cylinder  drains. 
One  of  the  principal  effects  of  clearance  is  to  make  the 
effective  or  actual  cut-off  later  than  the  apparent ;  that  is, 
the  cut-off  shown  by  the  indicator  card  is  but  the  "  apparent " 
cut-off,  while  the  "actual"  cut-off  is  a  longer  one,  as  shown 
on  Fig.  3,  as  follows  : 

Let  e  d  represent  the  stroke  of  a  piston,  and  assume  a 
cut-off  at  one-half  stroke  and  ten  per  cent,  clearance.  Then 
a  b  is  one-half  of  e  d,  and  the  apparent  ratio  of  expansion 


IO  COMPOUND    LOCOMOTIVES. 

is  2.  Lay  off  e  f  equal  to  one-tenth  of  e  d,  then  /  e  or 
a  g  represents  the  clearance.  The  volume  which  is  filled 
with  steam  when  cut-off  takes  place  is  g  b,  and  this  expands 
until  it  fills  the  volume  of  f  d.  The  actual  ratio  of  expan- 
sion is  therefore  /W  divided  by^-  d,  or  as  drawn  in  Fig.  3  it  is  : 


—  =—=  1.83  instead  of   2.     Expressing  this  as 
a  formula,  the  actual  ratio  of  expansion  is 


n+k 

in  which  k  is  the  clearance  expressed  as  a  decimal  of  the 
volume  displaced  by  the  piston  in  one  stroke,  and  n  is  the 
apparent  cut-off,  or  one  divided  by  the  apparent  ratio  of 
expansion.  The  point  c  on  the  expansion  curve  is,  of 
course,  higher  with  a  ratio  of  expansion  of  1.83  than  with 
a  ratio  of  2,  and  hence  the  mean  pressure  between  b  and  c 
is  higher.  In  making  calculations  the  actual  ratio  of  expan- 
sion should  of  course  be  used,  but  the  formula,  7,  will 
not  then  give  correct  results,  as  by  it  the  mean  pressure 
between  ^and  c  is  found,  and  not  that  between  a  and  c,  and 
a  correction  must  therefore  be  made  which  necessitates 
additional  calculation.  It  is  better  in  most  cases  to  make 
use  of  a  graphical  construction.  For  example,  see  Appen- 
dix G. 

5.  Construction  of  the  Expansion  Curve.  —  A  simple 
method  of  plotting  points  on  the  hyperbolic  expansion  curve 
is  the  following,  which  requires  only  a  triangle  and  a  straight 
edge  :  In  Fig.  3  let  0  V  be  the  zero  line  of  pressures,  0  P  the 
zero  line  of  volumes,  and  p  a  known  point  on  the  hyperbola. 
Through  p  draw  /  s  parallel  to  0  V,  making  it  of  any  con- 
venient length.  Draw/  k  and  s  t  perpendicular  to  O  J^and 
draw  0  s.  Through  the  point  u  where  0  s  crosses/  k,  draw 
u  q  parallel  to  0  V,  and  where  this  line  cuts  s  t  at  q  is  a 
second  point  on  the  curve.  Any  number  of  other  points 
can  be  found  from  p  or  q  in  a  similar  manner,  as  indicated 


CLEARANCE,  COMPRESSION,  EXPANSION.  I  I 

in  Fig.  3.  An  advantage  of  this  method  is  that  the  dis- 
tance of  a  point  from  0  P  can  be  selected  at  pleasure,  as  it 
will  be  always  directly  under  the  point  to  which  the  diag- 
onal is  drawn,  as  q  and  s,  or  x  and  w,  41,  43. 

6.  Compression. —  Compression  or  cushioning  in  com- 
pound locomotives  is  a  factor  of  steam  distribution  which 
it  is  more  difficult  to*  dispose  of  satisfactorily  than  in  single 
expansion  engines.  For  economy  of  steam,  the  pressure  in 
the  clearance  space,  when  the  steam  valve  opens,  should 
not  be  far  from,  but  somewhat  less  than,  the  initial  pressure, 
while  the  necessary  pressure  for  "cushioning"  the  recipro- 
cating parts  is  a  problem  in  itself,  and  is  generally  regulated 
by  the  lead  of  the  valves. 

In  a  single  expansion  engine  having  an  initial  pressure 
of  175  pounds  absolute,  and  a  back  pressure  of  18  pounds 
absolute,  it  is  possible  to  compress  to  9.7  times  the  back 
pressure  before  the  initial  pressure  will  be  exceeded.  But 
in  a  compound,  if  the  receiver  pressure  is  70  pounds  abso- 
lute, the  possible  range  of  compression  is  for  the  h.  p.  cyl- 
inder from  70  to  175  pounds,  and  for  the  1.  p.  cylinder  from 
1 8  to  70  pounds,  or  2.5  times  in  the  former,  and  about  3.9 
times  in  the  latter.  It  will  be  at  once  apparent  that  the 
valve  adjustment  for  compression  in  the  compound  is  a 
much  more  difficult  problem  than  in  the  single  expansion 
engine. 

For  example,  with  5  per  cent,  clearance  in  a  compound 
and  the  pressures  as  just  stated,  the  pressure  in  the  clear- 
ance space  at  the  end  of  the  stroke  would  equal  the  initial 
pressure  in  the  h.  p.  cylinder  when  the  exhaust  closed  at 
2.5  X. 05  —  .05  =  . 075  of  the  stroke  from  the  end,  or  at  92.5 
per  cent,  of  the  stroke,  as  it  is  frequently  stated.  In  the 
1.  p.  cylinder,  an  exhaust  closure  at  85.5  per  cent,  would  fill 
the  clearance  space  with  steam  at  receiver  pressure.  With 
10  per  cent,  clearance,  and  the  same  pressures  as  before, 
the  earliest  allowable  points  of  exhaust  closure  would  be  85 


12 


COMPOUND    LOCOMOTIVES. 


per  cent,  in  the  h.  p.  and  71  per  cent,  in  the  1.  p.  cylinder. 
It  is  practically  impossible  to  get  such  late -exhaust  closures 
at  early  cut-offs  with  a  link  motion,  73-81. 

It   will   be   seen  from  this   that  a   large  percentage   of 
clearance  in  a  compound  engine  will  reduce  compression 


750 


50 


%T 


•25  ,50  .75 

Volume  in  Cubic  jeet 

FIG.   4. 
Actual  Curve  of  Compression. 

and  may  be  a  positive  advantage,  so  far  as  the  distribution 
of  power  between  the  cylinders  is  concerned,  also  large 
clearance  spaces  assist  in  the  reduction  of  high  compres- 
sion at  fast  speeds. 

An   approximation   to   the  relations   between   the   back 


CLEARANCE,  COMPRESSION,  EXPANSION.  13 

pressure,  the  pressure  from  compression,  the  point  of  ex- 
haust closure  and  the  clearance,  can  be  expressed  in  a  gen- 
eral formula  as  follows:  Referring  to  Fig.  3,  let/'  repre- 
sent the  back  pressure  and  p"  the  pressure  in  the  clearance 
space  at  the  end  of  the  compression,  both  measured  from 
the  zero  line  of  pressures  ;  let  /  be  the  point  of  exhaust 
closure,  Im  the  compression  curve  which  is  considered  as  a 
rectangular  hyperbola,  d  e  the  stroke  of  the  piston,  and  / e 
equal  k,  the  clearance  as  before.  Then  the  fraction  of  the 
stroke  at  which  the  exhaust  should  close  to  produce/"  is: 

47—  (^-¥ 

It  should  be  remembered  that  this  formula  is  but  an 
approximation,  as  the  real  compression  curve  is  not  a  rectan- 
gular hyperbola,  but  has  more  nearly  the  form  of  the  lower 
curve  in  Fig.  4.  This  modification  of  the  compression 
curve  is  produced  by  the  cooling  action  of  the  walls  of  the 
cylinder,  the  face  of  the  piston,  and  the  walls  of  the  steam 
passages,  all  of  which  have  to  be  heated  to  the  tempera- 
ture of  the  steam  which  rises  during  compression.  This  dif- 
ference between  actual  and  hyperbolic  curves,  in  Fig.  4, 
indicates  a  loss  due  to  clearance.  Clearance  compels  com- 
pression, and  compression  carries  with  it  this  type  of  loss. 

The  problem  of  determining  the  amount  of  compression 
necessary  to  cushion  the  reciprocating  parts  does  not  differ 
essentially  in  compound  and  single  expansion  engines, 
except  that  with  compounds  the  weight  of  the  reciprocating 
parts  is  necessarily  greater. 

To  further  illustrate  the  difference  between  the  actual 
curve  of  compression,  and  the  hyperbolas  drawn  from  any 
point  in  that  curve,  and  to  show  the  decrease  of  steam 
weight  during  compression,  reference  is  made  to  Figs.  5 
and  6,  which  show  some  actual  indicator  cards  taken  from 
a  locomotive.  The  actual  clearance  in  the  engine  is  8  per 
cent.,  and  is  represented  by  the  full  vertical  lines.  The 


COMPOUND    LOCOMOTIVES. 


FIG.  5. 
Difference  between  Actual  Curve  of  Compression  and  Hyperbol; 


CLEARANCE,  COMPRESSION,  EXPANSION, 


FIG.  6. 
Difference  between  Actual  Curve  of  Compression  and  Hyperbola. 


1 6  COMPOUND    LOCOMOTIVES. 

dotted  lines  for  comparison  with  the  curve  of  compression, 
are  hyperbolas,  one  of  which  is  drawn  from  a  point  of  the 
compression  curve  after  the  exhaust  valve  is  closed,  and  is 
based  on  the  actual  clearance.  This  dotted  line  is  always 
the  one  which  falls  inside  of  the  compression  curve.  The 
other  dotted  line  is  an  hyperbola  that  is  drawn  to  approx- 
imate closely  to  the  actual  curve  of  compression.  This 
second  line  is  drawn  from  the  same  point  of  the  actual 
expansion  curve  as  the  first  dotted  line,  and  the  clearance 
which  would  give  this  hyperbola  is  shown  by  the  dotted 
vertical  line.  This  would  indicate  that  an  approximation 
to  the  actual  curve  of  compression  may  be  made  by  assum- 
ing an  hyperbola  for  the  shape  of  the  curve  of  compression, 
and  changing  the  clearance  to  suit  ;  that  is  to  say,  the 
actual  compression  curve  approximates  to  an  hyperbola 
based  on  a  greater  clearance  than  is  actually  used  in  the 
engine  from  which  the  cards  were  taken.  The  amount  of 
this  greater  clearance  is  given  in  the  illustrations. 

These  comparative  lines  on  Figs.  5  and  6  are  hyper- 
bolas, and  therefore  show  less  decrease  in  weight  of  steam 
during  compression  than  would  be  shown  if  the  curve  of 
equal  steam  weight  had  been  used  for  comparison,  as  is 
evident  from  Fig.  23a. 


CHAPTER   III. 

MEAN  EFFECTIVE   PRESSURE. 

7.  Formula  for  Calculating  Mean  Effective  Pres- 
sure. —  For  calculating  the  pressures  at  the  various  points 
of  elementary  cards,  we  can  without  serious  error  make 
use  of  the  ordinary  formulas,  and  assume  that  pressures  of 
steam  vary  inversely  as  the  volumes,  the  curves  of  expan- 
sion and  compression  then  being  rectangular  hyperbolas. 
On  this  basis,  the  absolute  mean  pressures  for  such  lines 
as  a  b  c,  Fig..  3,  are  determined  by  the  formula:  43. 


This  will  be  recognized  as  the  ordinary  formula  for 
mean  pressures,  and  in  which  P  is  the  absolute  initial  pres- 
sure, r  is  the  ratio  of  expansion,  i.  e.,  volume  at  cut-off 
divided  by  volume  at  end  of  stroke  or  at  exhaust,  as  the  case 
may  be,  and  p  is  the  absolute  mean  forward  pressure.  The 
absolute  pressure  is  the  gauge  pressure  plus  the  atmospheric 
pressure,  which  is  practically  14.7  pounds  per  square  inch. 
The  term  "  hyperbolic  "  as  applied  to  logarithms  refers  to 
the  "  Natural  "  or  "  Naperian  "  logarithm.  An  example  of 
the  application  of  the  above  formula  will  be  found  in  Appen- 
dix A.  This  formula  is  applicable  to  such  lines  of  the  card 
as  a  b  c  when  a  b  is  parallel  to  the  atmospheric  line,  as  it  is 
practically  in  engines  supplied  from  a  boiler  and  working 
at  slow  speeds.  For  calculating  the  mean  pressure  between 
b  and  <:,  d  and  e,  e  and/^  or  for  other  expansions  or  compres- 
sions in  which  the  part  of  the  card  considered  is  wholly 

17 


18 


COMPOUND    LOCOMOTIVES. 


within  the  hyperbola,  and  where  the  line  of  constant  pressure 
as  a  b  is  not  included,  the  following  formula  is  to  be  used  : 

hyp.   log.   r 


r  — 


For  example  see  Appendix  B  and  Appendix  F. 

8.  Difference  Between  Calculated  and  Actual 
Mean  Effective  Pressure. —  The  foregoing  method  serves 
to  illustrate  what  the  action  of  steam  in  locomotive  cylin- 
ders is  frequently  assumed  to  be,  and  is  worth  perusal  by 
the  student  ;  but  for  actual  practice,  the  mean  effective  pres- 
sure in  either  cylinder  differs  so  much  from  that  given  by- 


FIG.    7. 

Reduction  of  M.  E.  P.  as  Speed   Increases. 

calculation,  that  the  only  safe  course  to  pursue  is  to  draw 
the  preliminary  indicator  cards  by  modifying  actual  cards, 
from  practice,  as  is  explained  further  on. 

As  a  more  forcible  illustration  of  this  difference,  Tables. 
B,  C,  D,  E,  F,  G,  and  H,  have  been  prepared  from  the 
actual  indicator  cards  Figs.  14  and  15,  taken  from  a  Sche- 
nectady  ten-wheel  two -cylinder  receiver  compound  on  the 
Central  Pacific  Railroad.  Columns  I,  K  and  L  show  how 
wide  is  the  variation  between  the  calculated  and  actual 
mean  effective  pressures  when  the  calculations  are  based  on. 


MEAN    EFFECTIVE    PRESSURE.  1 9 

the  elementary  indicator  cards.  Reference  to  these  tables  is 
also  made  under  the  head  of  "  Cylinder  Ratios,"  chapter  VII. 
9.  Decrease  of  Mean  Effective  Pressure  as  Speed 
Increases. —  Fig.  7  shows  the  decrease,  in  a  single  expansion 
engine,  of  the  maximum  mean  effective  pressure  per  square 
inch  of  piston,  with  the  best  and  the  ordinary  valve  gears, 


20000 


20  4O  6O 

SPEED  IN  MILES  AN  HOUR. 

FIG.  8. 
Reduction  of  Power  as  Speed  Increases. 

which  follows  an  increase  in  the  number  of  revolutions 
per  minute  of  locomotive  driving  wheels.  Boiler  pres- 
sure, 175  pounds  per  square  inch  absolute.  This  shows  the 
need  of  careful  attention  to  valve  gear  dimensions,  77-82. 
10.  Effect  on  Draw  Bar  Pull  of  Decrease  of  Mean 
Effective  Pressure  as  Speed  Increases. —  Fig.  8  shows 
the  decrease  in  the  maximum  pull  on  draw  bar  of  a  single 
expansion  engine  which  follows  an  increase  in  speed  of  a 
19X24  locomotive  with  5^  foot  driving  wheels,  with  the 
best  valve  gear  and  with  the  ordinary  valve  gear. 


2O 


COMPOUND    LOCOMOTIVES. 


11.  Increase  of  Per  Cent,  of  Total  Power  Consumed 
by  Locomotives  and  Tenders  which  follows  a  Decrease 
of  Mean  Effective  Pressure  Due  to  Speed. —  Fig.  9  shows 
how  the  per  cent,  of  total  power  generated  by  the  cylinders 
and  consumed  by  the  locomotive  and  tender  together,  in- 
creases as  the  speed  increases,  regardless  of  any  change  there 

PERCENT.  OF   TOTAL    CYLINDER  POWER 
CONSUMED     BY    CARS. 

2O  4O  6O  8O 


ftO 

"*•*• 

\ 

\ 

\ 

\ 

A 

\, 

X 

n 

y 

n 

^ 

4, 

2 

V 

& 

/. 

>rt» 

fiO 

X 

fc. 

? 

f 

*  I. 

N 

^ 

V 

\ 

sj 

(t. 

^ 

\ 

* 

\ 

T 

^ 

^ 

10 

^ 

->  \ 

\ 

\ 

^ 

Y 

Of) 

10( 

) 

8 

0 

6 

O 

4 

O 

2 

O 

( 

J 

PERCENT. OF    TOTAL  CYLINDER   POWER 
CONSUMED  BY   LOCOMOTIVE    AND    TENDER, 

FIG.  9. 
Per  cent,  of   Power  Consumed  by  Locomotive  at  Various  Speeds. 

may  be  in  train  resistance.  This  is  readily  deduced  from  Fig. 
8  by  comparing  the  total  draw  bar  pull  with  the  approxi- 
mate locomotive  resistance. 

It  is  clear  from  these  diagrams  that  at  high  speeds  almost 
the  entire  power  of  the  locomotive  cylinders  is  consumed 
by  the  locomotive  and  tender,  not  because  the  head  air 


MEAN    EFFECTIVE    PRESSURE. 


21 


resistance,  or  the  locomotive  and  tender  resistance,  increases 
greatly,  but  almost  solely  because  of  the  decrease  of  mean 
effective  pressure  in  the  cylinders  brought  about  by  wire- 
drawing, compression  and  early  cut-off  at  high  speeds.  The 
worse  the  design  of  valve  motion  and  steam  passages,  the 
sharper  will  be  the  inclination  of  the  curve  in  Fig.  9  to  the 
1-eft.  A  misunderstanding  of  the  real  condition  on  the  part 
of  some  writers  has  led  to  the  conclusion  that  this  inclina- 
tion is  due  to  a  great  increase  in  head  air  resistance  The 
fallacy  of  such  a  conclusion  appears  at  once  from  an  exam- 
ination of  Figs.  7,  8  and  9. 

Fig.  10  shows  the  advantage  of  using  a  large  driving 


3O      35       4O      45       SO      55      €0      65       TO      75       8O 
SPEED  IN  MILES  AN  HOUR. 


85      90     85      100 


FlG.     10. 

Effect  of  Large  Drivers  on  M.  E.  P.  at  High  Speed. 

wheel  on  a  locomotive.  All  that  this  diagram,  Fig.  10, 
shows,  applies  with  greater  force  to  compounds,  as  the  loss 
in  power  with  compounds  increases  more  rapidly  as  the 
speed  increases  than  with  single  expansion  engines.  The 
mean  effective  pressure  given  in  Fig.  10  is  that  which 
will  be  obtained  when  the  steam  valves  are  controlled  by 
the  best  types  of  valve  motion  now  used,  and  when  the 
boiler  pressure  is  160  pounds  per  square  inch  by  gauge. 

Figs.  II  and  12  show  very  .  clearly  how  the  mean 
effective  pressure  is  reduced  as  the  speed  increases  in  a 
Vauclain  compound.  These  cards,  Nos.  I  to  13,  were  taken 
from  a  ten-wheel  freight  engine  on  the  Chicago,  Milwaukee 


22 


COMPOUND    LOCOMOTIVES. 


&  St.  Paul  road.  Table  A  gives  the  data  calculated  from 
these  cards,  and  Fig.  No.  13  is  a  diagram  showing  the 
decrease  of  mean  effective  pressure  as  the  revolutions  per 
minute  increase.  These  cards  are  intended  to  illustrate 


FIG.  ii. 
Actual  Indicator  Cards  Showing  Decrease  of  M.  E.  P.  as  Speed  Increases. 

what  takes  place  in  any  engine,  compound  or  single  expan- 
sion, as  the  speed  increases,  and  shows  how  the  hauling 
power  of  a  freight  engine  decreases  as  the  speed  increases. 
Card  No.  I  shows,  perhaps,  more  clearly  than  any  of  the 
others  how  compression  and  wire-drawing  robs  the  engine 
of  its  power  at  high  speed.  From  this  it  is  clear  that 
if  a  locomotive  is  proportioned  so  that  its  cylinder  power 


MEAN  EFFECTIVE  PRESSURE. 


10 


FIG.  12. 
Actual  Indicator  Cards  Showing  Decrease  of  M.  E.  P.  as  Speed  Increases. 


INVOLUTIONS  ren  MINUTC 


FIG.  13. 
Diagram  Showing  Decrease  of  Hauling  Power  as  Speed  Increases. 


COMPOUND    LOCOMOTIVES. 


at  low  speed  is  just  about  sufficient  to  slip  the  wheels,  it  will 
have  far  too  little  cylinder  power  to  slip  the  wheels  at  high 
speed.  This  then  is  an  illustration  of  the  need  of  an  increase 
of  cylinder  power  to  haul  heavier  trains  at  high  speeds,  and 
it  is  evident  that  the  simplest  and  best  way  to  increase 
the  cylinder  power  is  to  reduce  the  wire-drawing  and  com- 
pression. 

TABLE   A, 

Giving  Data  "with  Reference  to  Indicator  Cards  Nos.  i  to  /?,  taken  from 
a  Ten-Wheel  Vauclain  Compound  Freight  Engine  on  the  Chicago,  Milwaukee 
and  St.  Paul  Railroad. 


No.  of  card.     - 

i 

2 

3 

4 

5 

6 

7 

8 

9 

10 

ii 

12 

13 

No.  of    reverse 

lever     notch. 

i 

1 

i 

ifc 

*% 

i# 

2 

2^ 

2^ 

2^ 

2^ 

2^ 

7 

Cut-off  h.p.  cy- 

linder,inches. 

12.25 

12    25 

12    25 

13  25 

13.28 

1328 

14    25 

15    41 

J5  44 

IS  44 

I5-4I 

I5-4I 

21.62- 

Cut-off  1.  p.  cy- 

linder,inches. 

15.06 

15  oo 

15.06 

15  94 

15  9° 

*5-9° 

16.87 

17    62 

17  75 

*7  75 

!7-63 

I7.63 

22.75, 

Revolutions  per 

minute.    -    - 

256 

256 

228 

244 

232 

140 

188 

192 

172 

156 

120 

80 

48 

Boiler  pressure, 

absolute   -    - 

191 

I9I 

l85 

185 

183 

189 

192 

190 

192 

1  86 

190 

l85 

191 

Mean    effective 

pressure,  h.  p. 

cylinder. 

37  5° 

41    25 

4O.OO 

51  88 

47  50 

64.50 

68  75 

70.00 

75  °° 

78  75 

82.50 

81.25 

116.  25. 

Mean    effective 

pressure,  1.  p. 

cylinder.    - 

13  75 

12    50 

15  oo 

15  oo 

20.00 

25.00 

22    50 

28.75 

25  oo 

27  5° 

37.50 

38.75 

46.25 

Mean    effective 

pressure,  1.  p. 

cyl.,    reduced 

to  equivalent 

for  h.  p.   cyl. 
Prop  o  r  *  i  o  n  a  1 

40  43 

34  75 

44  10 

41.70 

58.80 

73-50 

62-55 

84    52 

69.50 

76.45 

110.25 

"3-93 

128.56 

No.    showing 

com  para  t  i  v  e 

haul  ing  power 

1.025 

I    CO 

i  107 

1.231 

1-399 

1.816 

I    728 

2.033 

i  .901 

2.042 

2.535 

2.568 

3.221 

Pressure  at    ad- 

mission to  h. 

p.      cylinder. 

165 

*75 

168 

178 

168 

173 

180 

170 

176 

171 

176 

168 

167 

CHAPTER  IV. 


DIFFERENCES    BETWEEN    ELEMENTARY   AND   ACTUAL 
INDICATOR  CARDS. 

12.  Difference  between  Apparent  and  Actual  Cut- 
off.— Figs.  14  and  15  show  a  set  of  actual  indicator  cards 
from  a  two-cylinder  receiver  compound  of  the  Schenectady 
type  on  the  Southern  Pacific  Railroad,  having  the  following 
general  dimensions  : 


Diameter  of  H.  P.  Cylinder      20 

"   L.  P.         "  29 

Stroke  of  Pistons  24 

Diameter  of  Drivers  69 

Number    "         "  6 

Weight  on          "  96,680 

"     of  Engine,  loaded  129,700 

'  Tender, 

Heating  Surface  1736.2 

Grate  "  29.26 

Heating  per  sq.  ft. 

of  Grate  60.7 

Heating  Surface  per  sq.  in. 

Cyl.  Area,  L.  P.  2.63 


inches  Outside  lap  of  Valve,  H.  P.   il/%  inches 

"   "      "    L.  P.  \y%     " 

Inside  Clearance,  H.  P.  j5^ 

L.  P.  ft       " 

Size  of  Steam  Ports,  H.  P.  Cyl.    2^x18 
Ibs.       "      "       "  "      L.  P.    "       2^x20 

"  Exhaust  '*      H.  P.  "  3x18 

"      L.  P.    "  3x20 

sq.  ft.  Cyl.  Area  per  sq.  in.  flue  open- 
ing 1. 1 1  sq.in 
Per  cent,  of  Weight  on  Drivers      74-54 
Clearance  H.  P.  Front           1026  cu.  in. 

"    "    Back  1178       " 

"  L.  P.  Front  1386 

"    "    Back  1220 


Table  B  shows  the  difference  between  the  "actual"  cut- 
off, taking  into  account  the  clearance,  and  the  "apparent" 
cut-off  measured  from  the  valve  motion  when  the  engine  is 
out  of  service,  and  ^  not  as  taken  from  indicator  cards,  and 
does  not  therefore  include  lost  motion  and  springing  of 
the  parts.  The  difference  between  these  is  so  great  as 
to  emphasize  the  need  of  always  basing  calculations  and 
examinations  on  the  actual  instead  of  the  apparent  cut-off. 
This  table  also  shows  the  effect  of  clearance  in  increasing 
the  actual  cut-off  beyond  the  apparent  cut-off. 

25 


26 


COMPOUND    LOCOMOTIVES. 


TABLE  B. 

Showing  the  difference  between  the  "Actual"  Cut-off,  counting  the  Clear- 
ance, and  the  "Apparent "  Cut-off,  Measured  from  the  Valve  Motion  when  the 
Engine  is  out  of  Service,  and  not  taken  from  Indicator  Cards. 


Actual 
Card  No. 

A 

Revolutions 
per 
minute. 

B 

Miles  per  hour. 

E 

Piston    speed   in 
feet  per  minute. 

c 

Actual  cut-off 
including  clear- 
ance.    Per  cent. 
HP      L  P 

D 

Apparent  cut-off 
Per  cent. 

HP        L  P 

I 

2 
3 

4 

6 

7 
8 
9 

30 
50 
60 
144 
1  80 
240 
240 
300 
330 

6.16 
10.26 
12.32 
29.56 

36.95 
49.27 
49.27 
61.58 
67.74 

120 
200 
240 

576 

720 

960 
960 

1200 
1320 

86.4 
83.8 
76.6 
68.2 
58.4 
58.4 
50.2 
50.2 
50.2 

87.3 
84.2 

78-5 
71.2 
61.6 
61.6 

55-1 
55-1 
55-i 

84.5 
81.2 

73-o 
63-5 
52.1 
52.1 
42.7 
42.7 
42-7 

86. 
82.8 
76.8 
68.8 
58.5 
58.5 
51-5 
51-5 
5i-5 

13.     Difference   between    Actual    and    Elementary 
Mean  Effective  Pressures  in  High- Pressure  Cylinder. — 

Table  C  gives  the  elementary  or  theoretical  mean  effective 

TABLE*  C. 

Showing  the  Elementary  or  Theoretical  Mean  Effective  Pressure  in  the 
High- Pressure  Cylinder,  based  on  the  Elementary  Indicator  Cards  and  on 
Boiler  Pressure. 


C(h.p) 

F 

G(hp) 

H 

I 

K 

L 

Fi 

Is  ^ 

jo*-- 

jw"! 

'£.     V 

y-^J  8  ^  g  g 

I.S-S 

"s  3-- 

t;  1  S 

1  & 

«sr 

«| 

N 

*  ^  s|  o-| 

iC   ^   ^ 

1  11 

c||| 

d 
fc 

i* 

s  S3 
</>  a. 

|| 

•|f2 

i^g'G^ll.s 

cd| 

|*| 

^      iT  **  i— 

M   0   >> 

1 

S1*"1 

If 

£1 
a| 

Ej 

aj^.S 

rt  fij 

'"  "Z  «       8      !y  8J 

u  ^  Ja    ^  £     <<  a 

Si 

l]jj 

—  5^2  u 
.0  SS"S  d 

o 

I  js 

c 

oj     . 

If 

60 

rt  "g     C/3 

•II 

S?« 

%ii!il 

"^  1  S3 

S3  e  «  ^ 

411 

: 

86.4 

152 

151 

58 

92.3 

89.1 

96.8 

165-3 

2 

83.8 

142 

142 

54 

84.9 

83.2 

98.0 

153-9 

3 

76.6 

152 

152 

54 

93-o 

83.0 

89.2 

162.0 

4 

68.2 

150 

149 

50 

88.5 

83.6 

94-5 

153-5 

5 

58.4 

I  60 

157 

47 

93-8 

54-2 

57-8 

155.8 

6 

58.4 

I  60 

1  60 

46 

94-8 

42.4 

44-7 

155-8 

7 

50.2 

I  60 

1  60 

46 

86.0 

32-9 

38.3 

147.0 

8 

50.2 

I  60 

1  60 

45 

87.0 

31-3 

36.0 

147.0 

9 

50.2 

165 

165 

45 

91.2 

31.0 

34-0 

151  .2 

ELEMENTARY    AND    ACTUAL    INDICATOR    CARDS.       27 


pressure  in  the  h.  p.  cylinder,  based  on  elementary 
indicator  cards  and  on  boiler  pressure,  and  includes  no  con- 
sideration of  clearance  or  compression,  the  back  pressure 
being  taken  equal  to  the  average  receiver  pressure.  This 
is  compared  with  the  actual  mean  effective  pressure,  and 
shows  how  great  is  the  reduction  of  power,  and  to  some 
extent  economy,  resulting  from  wire-drawing  and  com- 
pression. 

TABLE   D. 

Showing  the  Theoretical  Mean  Effective  Pressure  in  the  High-Pressure 
Cylinder,  based  on  the  Elementary  Indicator  Card,  and  with  other  assumptions 
used  for  Table  C. 


C  (h.  p.) 

F 

G  (h.  p.) 

H 

J 

K 

M 

bfi 
C 
'O 

3 
"u 

-I 

rt 

CUD 

II 

i! 

>  S3  «  i'S  Ji'-o 

||:IHi 

V     • 

•=l 

If 

.§5d 

H  £* 

o  —  e 

0 

•sg 

O   y 

£. 

K-S 

SJ 

^ 

|l 

id|llig- 

«  51 
Bft-S 

iij 

•E 

tj 

«  sr 

ijj 

s  y 

_  x  «  £  a  8  '^ 

l-fig" 

6 

ft  W 

D  t/5 

^ 

i-sc^|ii 

^•Sft 

g'll  _ 

"« 

g   C 

_S  « 

^    • 

2  &c 

2-   H   ^    &£^Q   rt    ^  *^ 

«  w 

U  QJ  ^  a; 

2 

tl  2 

SB 

S  3-a 

o 

JH   « 

rh    &JO-" 

U   x   S 

«  S  5  c 

<j 

<  s 

PQ  ^ 

O  c   . 

<J     2n         . 

f^Snuo^Urt^fa 

^  ™  o^, 

"y 

fin 

'5  sr 

S^ 

a^  'Si  «  2  ^  o. 

ft(£ 

I 

86.4 

152 

151 

58 

91-3 

89.1 

97-8 

2 

83.8 

142 

142 

54 

84.9 

83-2 

98.0 

3 

76.6 

152 

'52 

54 

93-o 

83.0 

89.3 

4 

68.2 

150 

149 

50 

87-5 

83.6 

95-6 

5 

58.4 

I  60 

157 

47 

91.1 

54-2 

59-5 

6 

58.4 

I  60 

1  60 

46 

94.8 

42-4 

44-7 

7 

50.2 

I  60 

1  60 

46 

86.0 

32.9 

.      38.3 

8 

50.2 

I  60 

160 

45 

87.0 

3i-3 

36.0 

Q 

50.2 

165 

165 

45 

91.2 

31.0 

34-0 

Table  D  shows  the  theoretical  mean  effective  pressure 
in  the  h.  p.  cylinder  based  on  elementary  indicator  cards 
and  on  the  pressure  at  the  beginning  of  the  stroke, 
and  with  the  other  assumptions  used  for  Table  C.  This 
shows  the  loss  in  power,  and  to  some  extent  economy, 
resulting  from  wire-drawing  and  compression.  The  close 
approximation  of  the  results  given  in  Tables  C  and  D  is  due 
to  the  important  fact  that  this  two-cylinder  compound,  Figs. 
14  and  15,  has  very  large  throttle  valve  and  steam  pipes, 


28 


COMPOUND    LOCOMOTIVES. 


CLCArtANCt. 

-l026cu.iNS. 

/MX..P.' 

•87.574 

MJC..P.' 

90.53SN 

1  CLEARANCE. 
1-1176  cu.  INS. 

120 
100 

£0 
60 

^Q 

f9 

1 

\ 

1 

\ 

A 

84.195^- 

7^  

^  

^L& 

120 

s~ 

^y 

_qo 

130 
0 

\/ 

8ljS3t  \/ 

A\ 

/v 

F.END. 


eo. 
50 

lo 

IO 

TcT 

45044  / 

^^-r^ 

^^  -~— 

^5^6^ 

^^ 

^X 

(/ 

\ 

f\ 

7 

^-X^ 

j~~* 

54.36  ><^^^  54.07 


J\ 


160 


£5.756 


FIG.  14. 
Indicator  Diagrams  from  Two-Cylinder  Receiver  Compound. 


ELEMENTARY    AND    ACTUAL    INDICATOR    CARDS.       2Q 


F  END. 


B.END. 


6. 


M.EJ?-  agaeg 


ifl  !Sf 

ZIOO 


B.  END. 


60 


n 


UK. 


7. 


9. 


FIG.  15. 
Indicator  Diagrams  from  Two-Cylinder  Receiver  Compound. 

and  was  operated  with  a  full  open  throttle.  There  was  but 
little,  if  any,  loss  in  steam  pressure  between  the  boiler 
and  the  steam  chest. 

14.  Differences  between  Actual  and  Elementary 
Mean  Effective  Pressures  in  Low-Pressure  Cylinder.— 
Table  E  gives  the  theoretical  mean  effective  pressure  in 
the  1.  p.  cylinder  based  on  the  average  receiver  pressure, 
the  actual  cut-off,  and  on  5  pounds  per  square  inch  back 
pressure,  and  the  other  assumption  used  for  Tables  C  and  D. 


30 


COMPOUND    LOCOMOTIVES. 


This  shows  the  loss  in  power,  and  to  some  extent  the  loss 
in  efficiency  in  the  1.  p.  cylinder  due  to  wire-drawing  and 
compression,  and  shows  the  futility  of  any  attempt  to 
use  the  common  theory  of  steam  engines  deduced  from 
elementary  indicator  cards  when  designing  compound 
locomotives  under  the  ordinary  conditions  and  with  the 
ordinary  valve  gears  and  ports. 


TABLE    E. 

Showing  the  Theoretical  Mean  Effective  Pressure  in  the  Low-Pressure 
Cylinder,  based  on  the  Average  Receiver  Pressure,  the  Actual  Cut-off,  on 
Five  Pounds  per  Square  Inch  Back  Pressure,  and  the  other  Assztinption  w-.9<:Y/  for 
Tables  Cand  D. 


C   (1.  p.) 

H 

N 

0 

P 

E  i 

0 

£ 

•o 

II 

u  w 
.£  2fc 

8  «'" 

4)    M  0- 

MjfjHiJ 

c  s    • 

11*1 
«-  D    ^  g 

e  i>  •    •   ^ 

8  =  oM 

i|2|| 

5 

?£ 

u  u 

—             X 

4)          V 

.5  &  «  "'  a-"  |  n 

-  $-  ? 

"o  c  jf'n  ^ 
*:  S  5  -2  -a 

"5a?^  » 

—                   n 

of  -a        yudo      ~-^>    •  c. 

-  ^^0- 

S  E  *  °.S 

w      ^^  T 

r; 

< 

1    61  1 

<^  h 

£5-3       |g.2    :_McSl'g- 

^  "  §       E  ^~  «'«-'"  y  *  '' 
"^QJ^         r"^  H-  **  «  y  e    '^^ir 

~    >         a- 

5"s^f"^ 

u    U          O  ^^ 

S-^s^-S 

H'^^3 

!       -Scu 

*sj  —  2-i 

S~i_: 

^SiS 

i 

87-3 

58 

52.3 

50.9 

97-4 

52.4 

2 

84.2 

54 

49.6 

46.2 

93-o 

49-5 

3 

78.5 

54 

47-6 

44.8 

94.0 

49-5 

4 

71.2 

50 

41.8 

32.5 

77-6 

47-4 

5 

61.6 

47 

36.4 

24.4 

67.1 

42.8 

6 

61.6 

6 

35-5 

20.1 

56.6 

43-8 

7 

55-i 

46 

33-7 

16.4 

48.6 

39-o 

8 

55-i 

45 

32.8 

13.2 

40.3 

37-2 

9 

55-  i 

45 

32.8 

15-4 

46.9 

39-8 

Table  F  gives  the  theoretical  mean  effective  pressure 
in  the  1.  p.  cylinder,  based  on  the  admission  pressure, 
and  with  the  other  assumption  as  given  for  Table  E.  This 
table  also  shows  the  loss  in  power  and  to  some  extent 
the  loss  in  efficiency,  resulting  from  compression  and  wire- 
drawing in  the  1.  p.  cylinder. 


ELEMENTARY    AND    ACTUAL    INDICATOR    CARDS. 


TABLE    F. 

Showing  the  Theoretical  Mean  Effective  Pressure,  in  the  Low-Pressure 
Cylinder,  based  on  the  Admission  Pressure,  and  with  the  other  Assumption 
given  for  Table  £. 


£ 

C  (1.  p.) 

H 

D  i 

o 

Theoretical  mean  effective  pressure 

1 

3 

Actual    cut-off 
including    clear- 
ance.    Per   cent. 

Average      r  e  - 
ceiver     pressure, 
gauge.      Pounds 
per  .sq.  in. 

for  1.  p.  cylinder,  based  on  admission 
pressure,    on  5   Ibs.  per  sq.   in.  back 
pressure,  and  on  the  same  compres- 
sion that  is  found  in  Corliss  engines. 

Actual      mean 
effective    pressure 
in    1.    p.    cylinde". 
Pounds  per  sq.  in. 

< 

Pounds  per  sq.  in. 

I 

87-3 

58 

52.3 

50.9 

2 

84.2 

54 

49-5 

46.2 

3 

78.5 

54 

49-5 

44.8 

4 

71.2 

50 

47-4 

32.5 

5 

61.6 

47 

42.8 

24.4 

6 

61.6 

46 

43-8 

20.  I 

7 

55-i 

46 

39-0 

I6.4 

8 

55-i 

45 

37-2 

13.2 

9 

55-i 

45 

39-8 

15-4 

15.  Differences  Between  Actual  Work  done  in  Cylin- 
der and  the  Work  shown  by  Elementary  Indicator  Cards. 

—Table  G  shows  the  difference  between  the  actual  work 
done  in  both  cylinders  of  the  compound  two-cylinder  loco- 
motives under  consideration,  and  the  work  that  would  be 
given  by  calculation  based  on  elementary  indicator  cards 
in  which  the  steam  was  assumed  to  expand  from  the  vol- 
ume at  cut-off  in  the  h.  p.  cylinder,  and  with  the  pressure  at 
admission  in  the  h.  p.  cylinder,  to  the  volume  correspond- 
ing to  the  final  volume  of  the  1.  p.  cylinder,  and  illustrates 
the  errors  in  some  of  the  theoretical  formulas  offered  for 
compound  locomotives,  more  particularly  in  foreign  tech- 
nical publications.  Such  formulas  as  these  have  been  used 
in  argument  about  compound  locomotives,  and  have  gener- 
ally led  to  conclusions  entirely  different  from  the  results  of 
actual  trials  of  real  locomotives. 

To  some  extent  this  table  also  shows  the  loss  in  effi- 
ciency of  compound  locomotives  due  to  inadequate  valve 
motion,  steam  passages,  and  high  speed,  when  compared  to 
a  good  stationary  compound  engine,  or  a  marine  compound 
having  better  valve  motion  and  running  at  slower  speed. 


COMPOUND    LOCOMOTIVES. 


TABLE    G. 


Showing  the  Difference  between  the  Actual  Work  done  in  both  Cylinders,  and 
the  Work  that  would  be  given  by  Calculation  based  on  Elementary  Indicator 
Cards. 


0 

*r. 

Z 

A  i 

B   i 

C  i 

Actual  Card  ] 

Absolute  pres- 
sure at  admission, 
h.  p.  cylinder. 

Absolute  pres- 
sure   at    end    of 
expansion,  1.    p. 
cylinder. 

Actual  work  done  in 
both       cylinders      per 
revolution,  foot  pounds, 
calculated  for  the  pur- 
pose     of      comparing 
with   column  (C  i). 

Theoretical  work  in  both  cylin- 
ders based  on  expansion  in  ele- 
mentary    engine     from      actual 
pressure  at   admission   in    h.    p. 
cylinder,  to  pressure  correspond- 
ing to  final  volume  in  1.  p.  cylin- 
der, including  clearance. 

I 

166 

55 

246,000 

467,000 

2 

157 

55 

226,100 

433,000 

3 

167 

49 

222,300 

439,000 

4 

164 

40 

190,500 

389,000 

5 

172 

30 

132,300 

383,000 

6 

175 

30 

106,300 

393,000 

7 

175 

25 

84,700 

353,000 

8 

175 

23 

74,200 

353,ooo 

9 

180 

23 

79,600 

364,000 

However,  the  difference  in  the  power  as  given  does  not 
represent  fairly  the  loss  in  efficiency.  Loss  in  power  does 
not  necessarily  indicate  loss  in  efficiency ;  in  fact,  the  loss 
in  efficiency  is  very  much  less  than  the  loss  in  power  indi- 
cated by  this  table. 

16.  Indicator  Cards  in  Practice. — In  making  a  theo- 
retical analysis  of  a  proposed  design  of  compound  engine, 
the  most  important  thing  to  do  is  to  bear  in  mind  the  dif- 
ference that  exists  between  elementary  indicator  cards, 
on  which  such  mathematical  analysis  is  generally  based,  and 
actual  indicator  cards  from  practice.  The  causes  which 
produce  the  differences  are  chiefly  the  initial  condensation, 
re-evaporation  during  expansion,  the  size,  shape  and  loca- 
tion of  the  steam  passages  and  receiver ;  the  opening  of 
the  exhaust  before  the  end  of  the  stroke ;  compression  and 
wire-drawing  due  to  the  slow  opening  and  closing  of  the 
ports,  as  well  as  the  effect  of  the  steam  distribution  bv  the 
existing  types  of  valve  motion.  The  following  are  some 
examples  of  the  differences  usually  found  between  the  ele- 
mentary and  the  actual  indicator  cards : 


ELEMENTARY    AND    ACTUAL    INDICATOR    CARDS.       33 

17.  Drop  in  Pressure  During  Admission,  High-Pres- 
sure Cylinder. — Fig.  16  shows  an  indicator  card  from  a 
compound  locomotive  in  which  steam  was  cut  off  at  about 
-fa  of  the  strpke  in  both  cylinders,  as  shown  by  the  full  line. 
The  clearance  space  is  10  per  cent,  of  the  piston  displace- 
ment in  the  h.  p.  cylinder,  and  7.5  per  cent,  in  the  1.  p. 


FIG.   1 6. 
Cards  Showing  Drop  of  Pressure  During  Admission. 

cylinder.  The  volume  of  the  receiver  is  one  and  one-half 
times  the  h.  p.  cylinder.  With  this  data  the  theoretical 
lines  shown  dotted  in  the  figure  have  been  constructed, 
making  allowance  for  the  excessive  drop  shown  between 
the  two  cards.  The  differences  between  the  actual  admis- 
sion and  expansion  lines  of  the  h.  p.  card  are  the  same  as 
in  cards  from  single  expansion  engines,  and  are  due  to  the 
wire-drawing  during  admission  and  at  cut-off,  and  to  the 
re-evaporation  during  expansion. 

18.  Rise  in  Pressure  During  Admission,  Low-Pres- 
sure  Cylinder. — It  will  be  seen  from  indicator  cards,  Figs. 
14  and  15,  that  there  is  an  increase  in  pressure  in  the  1.  p. 


34 


COMPOUND    LOCOMOTIVES. 


cylinder  and  in  the  receiver  after  the  1.  p.  piston  has 
moved  somewhat  from  the  end  of  the  stroke.  This  is  per- 
haps more  pronounced  in  card  No.  I,  Fig.  14,  taken  at  slow 


FIG.  17. 
Difference  Between  Actual  and  Elementary  Admission  and  Expansion  Lines. 

speed.  This  arises  from  the  fact  that  the  opposite  end  of 
the  h.  p.  cylinder  exhausts  at  this  time,  and  thus  increases 
the  steam  pressure  in  the  receiver,  and  also  in  the  1.  p. 
cylinder.  This  action  will  always  be  found  when  the 
exhaust  from  the  h.  p.  cylinder  takes  place  before  cut-off 
in  the  1.  p.  cylinder.  This  action  is  called  "re-admission." 
It  is  not  likely  that  with  the  ordinary  valve  gear,  the  h.  p. 
exhaust  in  any  compound  locomotive  will  occur  later  than  at 
90  per  cent,  of  the  stroke,  and  the  1.  p.  cut-off  will  not  gen- 
erally be  earlier  than  -^  of  the  stroke,  and  hence  it  is 


ELEMENTARY    AND    ACTUAL    INDICATOR    CARDS.       35 

safe  to  say  that  re-admission  will  always  occur  in  prac- 
tice. The  practical  effect  of  this  is  to  make  the  1.  p. 
admission  line  more  nearly  parallel  with  the  atmospheric 
line,  or,  in  other  words,  causes  the  1.  p.  admission  line  to 
more  nearly  resemble  the  admission  line  of  a  card  from  a 
single  expansion  engine. 

In  Fig.  17  are  shown  the  admission  and  expansion  lines 
of  four  indicator  cards  from  the  1.  p.  cylinder  of  a  com- 
pound locomotive.  The  points  of  cut-off  given  are  those 
which  were  recorded  on  the  cards.  The  dotted  lines  indi- 
cate the  form  of  the  theoretical  card  for  these  points  of  cut- 
off and  for  the  initial  pressures  as  shown. 

On  card  No.  6  a  curve  which  agrees  with  the  actual 
curve  very  closely  is  indicated  by  dots,  and  shows  an  ear- 
lier cut-off  than  that  recorded.  On  card  No.  9  the  irreg- 
ular dotted  line  shows  the  form  of  the  card  from  the  other 
end  of  the  cylinder  with  the  same  nominal  point  of  cut-off. 

19.  Effect  of  Speed  on  Shape  of  Indicator  Cards.— 
The  extent  of  departures  from  the  assumed  theoretical 
curve  varies  greatly  in  simple  engines,  and  principally 
depends  upon  the  piston  speed,  valve  gear,  and  size  of 
steam  passages.  The  only  satisfactory  way  of  determining 
the  probable  loss  in  a  proposed  engine,  whether  simple  or 
compound,  is  to  examine  indicator  cards  from  an  existing 
engine  of  the  same  general  proportions,  and  having  a  valve 
gear  of  the  same  type  and  dimensions.  Indicator  cards 
taken  from  engines  of  various  makes  when  on  similar  ser- 
vice show  variations  of  as  much  as  20  per  cent.,  and  it  is 
obvious  that  no  general  rule  can  be  laid  down  which  will 
give  the  results  that  may  be  expected  in  any  given  case,  as 
the  conditions  which  affect  the  actual  indicator  cards  are 
not  only  numerous  but  variable  as  well. 

For  example,  in  Fig.  16,  when  the  h.  p.  exhaust  occurs 
at  #,  the  1.  p.  piston  is  at  n,  and  re-admission  to  the  1.  p. 
cylinder  takes  place,  causing  a  rise  in  pressure  to  m.  The 


30  COMPOUND    LOCOMOTIVES. 

1.  p.  piston  moves  from  this  position  to  that  of  cut-off/ 
T40-  of  the  stroke,  before  the  h.  p.  piston  has  moved 
over  the  remainder  of  its  stroke  from  b  to  c.  The  pressure 
at  c  was  calculated  approximately  on  the  basis  of  the 
receiver  pressure  when  the  h.  p.  exhaust  opened,  being  that 
at  /  From  c  to  d  there  is  some  compression  as  shown. 


— 160 


H.  P.  Cut-off. 
L.P.     "     "      73% 
Rev.  p.  min.  147 


FIG.  1 8. 
Actual  Indicator  Cards  at  Different  Speeds. 

Turning  now  to  the  1.  p.  card,  and  taking  the  pressure  at  e 
as  that  of  the  steam  in  the  receiver,  we  find  that  the  line 
from  e  to  n  is  practically  at  constant  pressure,  and  that  the 
rise  in  pressure  from  n  to  m  is  comparatively  slight.  Also, 
that  during  the  expansion  of  the  steam  in  the  receiver  from 
m  to /the  fall  in  pressure  is  not  great.  The  drop  between 
the  h.  p.  and  the  1.  p.  cards  in  this  figure  is  excessive. 

In  Figs.  1 8  and  19  are  shown  indicator  cards  from  two- 
cylinder   compound   locomotives   at    different    speeds  and 


ELEMENTARY    AND    ACTUAL    INDICATOR    CARDS.       37 

points  of  cut-off.  The  shape  of  the  h.  p.  back-pressure  line 
is  to  be  noted.  Cards  Nos.  2  and  3  are  from  the  same 
engine,  and  it  will  be  noticed  that  the  compression  up  to 
about  the  middle  of  the  back  stroke  is  quite  marked,  and 


—  140 


H.  P.  Cut-off,  80°* 
L.P.  »  »  40% 
Kev.  p.  min.  160 


FIG.  19. 
Actual  Indicator  Cards  at  Different  Speeds. 

that  the  remainder  of  the  back  pressure  line  is  nearly 
horizontal,  as  it  was  found  in  Fig.  16.  In  Nos.  4  and  5  the 
compression  appears  to  continue  during  the  whole  of  the 
back  stroke.  This  is  the  case  in  a  considerable  number  of 
cards  which  have  been  examined,  and  is  particularly  notice- 
able at  high  speeds. 


CHAPTER  V. 

EFFECT    OF    CHANGING  THE    POINT  OF    CUT-OFF—PRESSURE 
IN  THE  RECEIVER. 

20.  Effect  of  Changing  Cut-off  in  Elementary  Engine. 

—Perhaps  the  clearest  way  of  indicating  the  general  effect 
on  the  work  done  in  the  cylinders  by  changing  the  point  of 
cut-off  is  to  analyze  the  elementary  engine  and  see  the 
effect  in  it.  In  practice  there  is  so  much  wire-drawing, 
particularly  in  the  1.  p.  cylinder,  that  a  change  in  the  point 


FIG.  20. 
Effect  of  a  Change  in  Point  of  Cut-Off. 

of  cut-off  does  not  affect  the  power  generated  in  the  cylin- 
der as  much  as  in  the  elementary  engine.  Also,  in  cases 
where  the  receiver  is  small,  a  change  in  the  cut-off  in  the 
1.  p.  cylinder  is  not  always  followed  by  a  proportionate 
change  in  the  mean  effective  pressure  in  that  cylinder 

To  illustrate  what  takes  place  in  the  elementary  engine 
when  the  cut-off  is  changed,  reference  is  made  to  Fig.  I. 
Under  the  conditions  assumed  for  that  illustration,  if  the 

38 


CHANGING    CUT-OFF — PRESSURE    IN    RECEIVER.       3Q 

h.  p.  cut-off  is  made  earlier,  while  the  1.  p.  cut-off  remains 
as  before,  at  one-half  stroke,  a  series  of  changes  will  be 
introduced,  which  are  shown  in  full  lines  in  Fig.  20,  the  lines 
of  Fig.  I  being  repeated  in  dotted  lines.  Assuming  a  cut- 
off at  3/6  stroke,  the  final  pressure  in  the  h.  p.  cyl- 
inder is  i6oxf=6o  pounds,  or  at  c'  instead  of  c.  Also, 
as  the  total  expansion  is  now  2.5  Xf  =2y°=6-f  instead  of  5, 
the  final  pressure  at  g  is  reduced  to  g' ,  which  represents 
1 60  X  2%-=  24  pounds.  Then,  as  the  1.  p.  cut-off  is  un- 
changed, the  pressure  at  /is  reduced  to  f ,  or  24x2  =  48 
pounds.  The  steam  which  fills  the  h.  p.  cylinder  at  a 
pressure  of  60  pounds  is  mixed  with  an  equal  volume  in  the 
receiver  at  a  pressure  of  48  pounds,  giving  a  resulting 
pressure  at  d  of  54  pounds.  The  results  of  this  change 
are,  then,  that  the  pressure  in  the  receiver,  the  initial  pres- 
sure in  the  1.  p.  cylinder,  and  the  mean  pressure  in  that 
cylinder,  are  all  less  than  before.  The  work  done  by  the 
1.  p.  cylinder  is  therefore  less,  while  for  the  h.  p.  cylinder 
we  have  taken  from  one  part  of  the  card  and  added  to 
another  part.  The  total  work  done  by  both  cylinders  is, 
of  course,  less  than  before,  but  the  proportion  done  by  the 
h.  p.  cylinder  is  greater,  and,  in  fact,  the  mean  effective 
pressure  in  that  cylinder  has  been  increased. 

With  both  cut-offs  at  the  same  point,  considerably  more 
work  is  done  in  the  1.  p.  than  in  the  h.  p.  cylinder,  but  by 
making  the  h.  p.  cut-off  the  earlier  of  the  two  there  is  less 
difference  in  work  than  before,  or,  in  other  words,  the  work 
may  be  equalized  by  this  means.  A  similar  effect  will,  of 
course,  be  produced  by  making  the  1.  p.  cut-off  later  than 
that  of  the  h.  p.,  and  conversely  by  making  the  1.  p.  cut-off 
earlier  than  that  of  the  h.  p.  the  proportion  of  the  total 
work  which  is  done  by  the  1.  p.  cylinder  will  be  increased. 
The  following  table,  calculated  for  R—2  and  C=i.$  v,  will 
illustrate  this : 


COMPOUND    LOCOMOTIVES. 


Showing  the  Effect  of  a 
Compound  Engine. 


TABLE    H. 

Change  in  Point  of  Cut-off  in    an   Elementary 


Cut 
h.  p. 

-off. 

I.  p. 

Mean 
press, 
h.  p. 

Mean 
press. 
1.  p. 

Mean  h.  p. 
press,  referred 
to  1.  p. 

Total  mean  in 
one  cyl. 

Prop 
of  \v 
h.p. 

Drtion 
ork. 
l.p. 

1- 

1 

46.6 

54-o 

23-3 

77-3 

•3 

•7 

& 

1 

51.4 

39-6 

25-7 

65-4 

•4 

.6 

f 

39-2 

48.9 

19.6 

68.4 

.29 

•7i 

i 

* 

31-5 

60.3 

15-7 

76.0 

.21 

•79 

21.  Effect  of  a  Change  of  cut-off  on  the  Receiver 
Pressure  in  an  Elementary  Engine. —  In  locomotive 
practice  the  pressure  in  the  receiver  is  less  than  that  cal- 
culated, on  account  of  losses  in  the  h.  p.  cylinder  and 
passages.  The  effect  of  a  lower  receiver  pressure  is  to 
increase  the  proportion  of  work  done  in  the  h.  p.  cylinder, 
so  that  by  adjusting  the  valve  gear  to  give  an  earlier  cut- 
off in  the  h.  p.  cylinder  than  in  the  1.  p.,  the  total  work 
may  be  very  nearly  equally  divided  between  the  two 
cylinders  of  an  elementary  engine,  and  can  be  divided 
with  sufficient  approximation  to  equality  in  a  well  designed 
locomotive. 

In  Figs.  I,  2  and  3  the  1.  p.  cut-off  has  been  taken  at 
one -half  stroke,  and  it  was  assumed  that  release  occurred 
in  the  h.  p.  cylinder  exactly  at  the  end  of  the  stroke.  If 
now  we  make  the  1.  p.  cut-off  later  than  one -half  stroke, 
leaving  everything  else  unchanged,  there  will  be  an 
exhaust  from  the  h.  p.  cylinder,  while  the  1.  p.  steam 
valve  is  still  open,  which  will  increase  the  pressure  in  the 
receiver  and  cause  what  may  be  called  a  re -admission  in 
the  1.  p.  cylinder.  This  is  illustrated  by  Fig.  22,  in  which 
the  h.  p.  exhaust  occurs  at  b,  causing  a  rise  in  pressure  to 
c,  from  which  there  is  expansion  as  before  in  the  h.  p. 
cylinder,  the  receiver  and  the  1.  p.  cylinder  until  the  1.  p. 
steam  valve  closes  at  d.  A  similar  effect  will  be  produced 
by  pre-release  in  the  h.  p.  cylinder.  See  Figs.  14  and  15. 


CHANGING    CUT-OFF PRESSURE    IN    RECEIVER.        4 1 

An  examination  of  a  diagram  such  as  Fig.  21  may  make 
this  subject  more  clear.  In  this  Fig.  b  c  represents  the 
stroke  of  the  pistons,  and  the  circle  the  path  of  the  crank 
pins.  Taking  the  direction  of  revolution  as  indicated  by 


FIG.  21. 
Diagram  of  Crank  Location,  Two-Cylinder  Compound. 

the  arrow,  when  the  h.  p.  piston  is  at  the  end  of  a  stroke, 
or  its  crank  is  at  a  c,  the  1.  p.  crank  will  be  at  a  c' ,  and  the 


FIG.  22. 
Rise  in  Pressure  During  Admission  to  1.  p.  Cylinder. 

exhaust  from  the  h.  p.  cylinder  which  takes  place  at  this 
position  of  the  cranks  will  cause  the  rise  in  the  1.  p.  card 
shown  at  c,  Fig.  22.  If  the  h.  p.  exhaust  occurs  before  the 
end  of  the  stroke,  for  example  when  the  piston  is  at  d, 
the  1.  p.  crank  will  be  at  a  e' ,  and  the  1.  p.  piston  at  g, 
causing  a  rise  in  the  1.  p.  card  as  shown  at  k,  Fig.  22.  In 
cards  taken  from  an  engine  this  increase  in  pressure  will, 
of  course,  be  more  gradual,  and  at  high  speeds  may  simply 
cause  the  1.  p.  admission  line  to  be  more  nearly  parallel 
with  the  atmospheric  line.  This  arises  from  the  high 


42  COMPOUND    LOCOMOTIVES. 

piston  speed  and  the  consequent  wire -drawing  of  the 
steam  through  the  ports  and  past  the  valves. 

22.  Equalization   of  Work  in   the   High   and    Low 
Pressure    Cylinders    of  a    Receiver    Compound.  —  The 

nearer  the  action  of  the  steam  in  a  compound  locomotive 
approaches  the  action  in  the  elementary  engine,  the  more 
readily  can  the  power  generated  in  the  two  cylinders  be 
equalized  at  all  cut-offs  by  an  alteration  of  the  cut-offs 
in  the  cylinders,  and  the  reverse  is  also  true  ;  namely, 
that  where  the  receiver  is  small  and  the  wire-drawing 
and  compression  excessive,  it  is  well  nigh  impossible 
to  equalize  the  power  generated  in  the  two  cylinders 
at  all  cut-offs  by  adjusting  the  cut-offs. 

Some  of  the  first  compounds  built  in  this  country  had 
much  wire -drawing  and  compression,  and  had  small 
receivers,  and  it  was  found  practically  impossible  to 
equalize  the  power  by  changing  the  cut-offs.  After  some 
considerable  experiment  the  receivers  were  increased  and 
the  compression  was  very  considerably  reduced  by  cutting 
out  the  inside  of  the  steam  valve,  more  particularly  on  the 
h.  p.  cylinder,  so  as  to  give  what  is  termed  "  inside 
clearance"  or  negative  lap,  80.  On  a  5^  inch  travel,  the 
amount  cut  out  on  each  side  was  as  much  in  one  case  as 
y2  of  an  inch.  This  clearance  delays  the  point  of  exhaust 
closure  and  decreases  the  amount  of  compression.  The 
result  of  these  changes,  when  taken  together  with  the  longer 
steam  ports  now  used,  has  been  to  put  the  two -cylinder 
compound  locomotive  at  this  time  in  very  good  shape,  so 
far,  at  least,  as  the  equalization  of  the  work  between  the 
cylinders  is  concerned.  This  appears  from  Table  I,  for 
instance,  which  shows  how  perfectly  the  work  is  equalized 
in  the  Schenectady  ten -wheel  compound  on  the  Central 
Pacific  Railroad. 

It  is  not  expected  that  when  a  locomotive  is  starting  a 
train  and  steam  is  used  directly  from  the  boiler  in  the  1.  p. 


CHANGING    CUT-OFF PRESSURE    IN    RECEIVER.        43 

cylinders,  that   the  work  will   be  equalized  in  the  h.  p.  and 
1.  p.  cylinders  of  any  compound  engine. 


TABLE    I. 

Showing  the  Equality  of  Work  in   the  High  and  Low-Pressure  Cylinders 
of  a  Schenectady  Two- Cylinder  Compound  Ten-Wheel  Locomotive. 


Cut-off  h.  p. 
Cylinder. 
Inches. 

Cut-off  I.  p. 
Cylinder. 
Inches. 

Per  cent,  of  total 
work  done  in 
h.  p.  Cylinder. 

Per  cent,  of  total 
work  done  in 
1.  p.  Cylinder. 

20^ 

20^8 

45-o 

55-0 

19%, 

•   19% 

45-8 

54-2 

17  y^ 

18/8 

46.5 

53-5 

l$l/i 

16^ 

47.8 

52.2 

12%, 

14^5 

51.0 

49-0 

12l/2 

I4M 

49-7 

50.3 

ic>X 

12/8 

48.5 

Si-5 

IOJ^ 

12/8 

52-7 

47-3 

ioX 

12/8 

48.5 

51-5 

23.  Equalization    of  Work  in    the  High   and   Low- 
Pressure  Cylinders  of  a  Non-Receiver  Compound. —  In 

the  four-cylinder  type  of  engine,  which  includes  the  tandem, 
Vauclain  and  Johnstone  compounds,  it  is  not  necessary, 
either  for  the  purpose  of  starting  trains  or  for  steadiness  of 
motion  of  the  engine,  to  equalize  the  work  done  in  the 
cylinders.  This  appears  from  the  fact  that  the  two  sides 
of  the  locomotive  are  duplicates  of  each  other.  However, 
in  the  Vauclain  engine,  in  order  to  favor  the  peculiar  con- 
struction of  the  crosshead,  in  which  the  centres  of  the 
piston  connections  do  not  coincide  with  the  centre  of 
the  main  road  bearing,  it  is  very  desirable  to  equalize  the 
pressure  at  all  parts  of  the  stroke  rather  than  the  zcw/£ 
done  per  stroke,  and  this  brings  in  a  new  problem  quite 
complicated  in  its  nature,  and  which  is  not  considered  in 
the  foregoing.  This  will  be  considered  in  the  description 
of  the  Vauclain  type  of  engine,  as  it  has  to  do  only  with 
that  particular  construction,  121. 


44 


COMPOUND    LOCOMOTIVES. 


24.  Conclusions    about   the   Equalization   of  Work 
in  High  and  Low-Pressure  Cylinders. —  In  the  two-cyl- 
inder receiver  compound  it  is  desirable  to  equalize  the  work 
done  at   all  points   of  cut-off  in   the   two  cylinders  except 
at  starting,  so   that  the  difference   will  not  be  more   than 
about  10  per  cent.  20-23.     In  the  tandem  compound,  it  is  not 
necessary  or  very  desirable  to  equalize  either  the  work  in 
the  cylinders  or  the  pressures  on  the  piston  rod.      In  the 
Vauclain   type   of  engine,  120,  it   is   not   necessary  or  very 
desirable  to  equalize  the  work  done  in  the  two  cylinders,  but 
it  is  quite  necessary  to  approximately  equalize  the  total  pres- 
sures on  the  piston  rods  at  different  points  of  the  stroke,  in 
order  to   prevent    a    twisting  tendency   of    the    crosshead. 
This  equalization  cannot  be  made  when  steam  is  admitted 
directly  from  the  boiler  to  the  1.  p.  cylinder,  yet  it  has  been 
quite  well  equalized  in  some  engines  when  running  under 
normal  conditions.      In   calculating  the  total  pressures  on 
the  piston   rod   of  the   Vauclain    engine   to   determine  the 
equalization,  it  is  necessary  to  include  the  pressures  on  the 
crosshead  which  result   from  the  inertia  of  the  piston,  and 
this  makes  the  calculations  rather  complicated.      In  a  high 
speed  engine,  such  as  a  locomotive,  the  inertia  of  the  piston 
rod  and  piston  modifies  materially  the  total  pressure  on  the 
piston  rods.     See  Appendix  P. 

25.  Pressure  in  the  Receiver. — The  variation  of   the 
pressure  in    the    receiver,    as    shown  on  the    lines  d,  e,  f, 
Fig.    I,   depends  upon  the  capacity  of    the    receiver  com- 
pared   with    the    capacity    of  the    h.   p,   cylinder    and    the 
1.    p.    cylinder     up     to    cut-off.       For     example,    see  Ap- 
pendix  E.     As    a    further  illustration  of  this,  the    follow- 
ing table   shows  the   pressure  at  the  points  d,  e  and  f,  with 
receivers  having  capacity    1.5   and   2  times  the  capacity  of 
the  h.  p.  cylinder  and  with  the  1.  p.  cylinder  capacity  from 
2  to  2.5  .times  the  capacity  of  the  h.  p.  cylinder,  53.      It  must 
be  remembered  that  the  results  in  this  table  are  based  upon 


CHANGING    CUT-OFF PRESSURE    IN    RECEIVER.        45 


elementary  indicator  cards  and  not  actual  indicator  cards, 
and  are  offered  only  in  the  way  of  illustration,  and  not  for 
guidance  in  actual  work,  12-19.  The  actual  pressure  in  the 
receiver  is  materially  modified  by  the  action  of  the  valve 
motion,  the  wire -drawing  of  the  steam  through  the  ports, 
and  the  compression  in  the  1.  p.  cylinder. 


Pressure 
atrf. 

Mean 
press.  bet. 
d  and  e. 

Pressure 
at  e. 

Mean 
press.bet. 
e  and/. 

Pressure 
at/. 

Mean 
press,  in 
receiver. 

C  —         v   R  —  2 

80 

01  8 

1  06  7 

01  8 

80 

91  8 

C  —  T  5  v   R  —  2  . 

80 

88  Q 

100 

88  9 

80 

88  9 

C  —  2      v   R  —  2  

80. 

87.4 

06. 

87  4 

80 

87  4 

C  —         v,  R  =  2.$  

72. 

82.6 

96. 

77-8 

64 

80.2 

C  =  2      v,  R  =  2.$  

69.3 

75-7 

83.2 

72.4 

64 

74. 

The  table  shows  that  the  receiver  pressure  may  vary 
during  one  stroke  as  much  as  27  pounds,  and  that,  gener- 
ally, the  pressure  at  /  the  cut-off  in  the  1.  p.  cylinder, 
will  be  below  the  admission  pressure  to  that  cylinder,  and 
while  it  would  appear  from  the  table  that  the  mean  pressure 
up  to  cut-off,  from  e  to  f,  does  not  differ  much  from  the 
mean  pressure  in  the  receiver,  yet,  in  fact,  there  is  a  con- 
siderable difference  between  these  mean  pressures,  because 
of  the  wire-drawing  of  the  steam  through  the  port  and  past 
the  valve  of  the  1.  p.  cylinder.  See  Figs.  14  and  15. 

In  designing  compound  locomotives,  the  pressure  in  the 
receiver  has  been  frequently  assumed  as  constant.  This 
assumption  gives  very  simple  formulas  for  receiver  capacity 
and  mean  effective  pressure,  yet  such  foimulas  have  no 
practical  application,  as  the  receiver  pressure  varies  con- 
siderably in  locomotive  work  owing  to  the  irregular  action 
of  the  valve  motion  and  the  wire-drawing  and  compression, 
12  19.  Some  technical  writers,  more  particularly  in  foreign 
publications,  have  deduced  some  quite  simple  mathematical 
expressions  for  the  proper  proportion  of  cylinder  volume, 
receiver  volumes,  and  points  of  cut-off,  but  these  formulas 


46  COMPOUND     LOCOMOTIVES. 

have  no  practical  application,  for  reasons  that  have  been 
given,  and  because  of  further  and  incidental  conditions  that 
are  imposed  on  locomotives.  See  Appendix  K. 

In  most  cases  it  is  well-nigh  impossible  to  pre-determine 
the  receiver  pressure  by  calculation,  and  the  only  safe  way 
to  proceed  is  to  select  actual  indicator  cards,  of  which 
there  are  now  a  great  many  available,  from  similar  engines 
in  practice,  arid  make  such  changes  in  the  actual  cards  as 
judgment  and  experience  dictate,  being  guided  in  this  by 
the  differences  between  the  proposed  design  and  the  actual 
similar  design  that  has  been  tested  in  practical  service. 
However,  the  table  shows  clearly  one  important  fact.  It  is 
that  the  larger  the  receiver,  the  smaller  are  the  variations 
of  pressure  in  it.  A  further  analysis  of  the  practice  in  this 
respect  is  given  under  45—56. 

Upon  the  receiver  pressure  depends,  to  a  great  extent, 
the  division  of  work  between  the  cylinders,  50-51,  and  in  an 
elementary  engine  or  a  slow  moving  locomotive  the 
division  of  power  may  entirely  depend  upon  this  factor ; 
but  in  an  actual  engine  moving  at  considerable  speed,  the 
wire -drawing  and  compression  so  modifies  the  action  of 
the  steam  that  the  control  of  the  power  distribution  does 
not  lie  with  the  receiver  pressure.  Any  useful  rule  for 
receiver  pressures  must  necessarily  be  based  almost  entirely 
on  the  results  from  actual  indicator  cards,  and  will  not  be 
applicable  to  engines  differing  much  in  design. 

If  the  pressure  maintained  in  the  receiver  of  an  engine 
in  practice  is  known,  the  probable  receiver  pressure  in  a 
similar  proposed  engine  can  be  predicted  ;  but  when  a 
quite  different  arrangement  of  valves  and  passages  is  used, 
the  distribution  in  previous  engines  will  be  of  little  service 
as  a  guide  in  making  estimates  of  receiver  pressures. 

When  a  compound  locomotive  is  moving  slowly,  the 
wire-drawing  and  compression,  6-11,  is  not  so  much  a  factor 
in  the  distribution  of  power  between  the  cylinders  and  in 


CHANGING    CUT-OFF PRESSURE    IN    RECEIVER.        47 

controlling  the  receiver  pressure,  and,  therefore,  an  approx- 
imate calculation  can  be  made  with  more  satisfaction  than 
for  conditions  when  the  locomotive  is  at  speed.  The 
following  is  a  method  of  approximating  to  the  probable 
receiver  pressures  at  slow  speeds: 

h.  p.  cut-off. 
P=C^  1.  p.  cut-off. 

In  this  formula  /  is  the  absolute  receiver  pressure,  />x 
the  absolute  h.  p.  initial  pressure,  and  c  is  a  numerical  co- 
efficient. 

An  examination  of  a  considerable  number  of  indicator 
cards  from  compound  locomotives  gave  an  average  value 
for  c  of  0.46,  but  this  value  is  not  recommended  except  for 
approximations,  and,  of  course,  no  such  formula  can  take 
the  place  of  direct  experiment. 

26.  Loss  Due  to  Drop  of  Pressure  in  Receiver. — The 
drop  of  pressure  into  the  receiver,  25,  represents  an  actual 
loss  of  efficiency,  since  it  occurs  by  the  expansion  of  the 
steam  without  doing  useful  work.  For  any  given  cut-off, 
or  position  of  the  reverse  lever  in  a  locomotive,  this  drop 
can  be  removed,  but,  in  doing  this,  other  losses  or  un- 
satisfactory actions  at  other  cut-offs  may  result,  which 
will  make  such  removal  of  drop  of  receiver  pressure  at  any 
particular  cut-off  undesirable.  A  method  of  calculating 
the  drop  in  the  receiver  from  elementary  indicator  cards, 
but  which  does  not  represent  actual  conditions,  is  given  in 
Appendix  E. 


CHAPTER  VI. 


COMBINED     INDICATOR     CARDS    AND    WEIGHT    OF     STEAM 
USED    PER    STROKE. 

27.  Combined  Diagram  Receiver  Type. — It  is  quite 
necessary,  in  order  to  understand  where  the  losses  are  in 
compound  locomotives,  to  construct  what  is  called  a 
"  combined "  indicator  card,  which  is  a  diagram  showing 


r^  n 


-dLLb- 


O' 

FIG.  23. 

Combined  Diagram  from  Two-Cylinder  Receiver  Compound. 

the  indicator  cards  from  both  h.  p.  and  1.  p.  cylinders, 
drawn  to  the  same  scale  and  compared  to  a  reference  curve 
in  the  matter  of  expansion.  In  this  way  the  expansion  of 
the  steam  in  the  two  cylinders  is  compared  approximately 
with  equal  expansion  in  a  single  expansion  engine,  45—46  ; 
however,  the  usefulness  of  such  diagrams  is  limited,  and, 

48 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    49 

.at  the  best,  they  only  show  the  serious  defects,  and  not  the 
minor  ones. 

28.  The  Rectangular  Hyperbola  as  a  Reference 
•Curve.  —  The  reference  curve  that  is  the  most  satisfactory 
•of  all  to  use  is  the  rectangular  hyperbola,  41,  the  method  of 
drawing  which  has  been  described  in  Fig.  3.  Fig.  23 
[illustrates  a  combined  diagram  from  a  two -cylinder 
Deceiver  compound  locomotive,  of  which  the  separate  cards 
as  taken  closely  resemble  Fig.  19,  card  No.  4.  In  making 
tthis  combined  diagram,  the  cards  are  drawn  to  the  same 
.scale  of  pressures  and  volume  as  follows  : 

Take  any  convenient  distance,  such  as  b  c,  to  represent 
rthe  volume  of  the  1.  p.  cylinder,  and  let  a  b  represent  the 
^volume  of  its  clearance  space.  Then  0  a  Pis  the  zero  line 
from  which  to  measure  volumes,  and  0  V  drawn  as  usual  is 
the  zero  line  of  pressures.  Lay  off  a  d  equal  to  the  h.  p. 
clearance  space,  and  d  e  equal  to  the  volume  of  the  h.  p. 
cylinder,  both  on  the  same  scale  as  that  of  the  1.  p. 
cylinder  ;  or  d  e  should  equal  b  c  divided  by  the  ratio  of 
the  cylinders.  The  outlines  of  the  cards  are  then  found  by 
plotting  points  as  usual. 

The  rectangular  hyperbola,  m  n,  for  instance,  is  not  a 
curve  that  corresponds  to  equal  steam  weights  at  different 
points,  but  to  the  contrary,  rises  above  the  curve  of  equal 
.steam  weights,  and  therefore  approximates  more  nearly  to 
£he  real  curve  of  expansion  in  the  simple  engine  than  the 
other  curves  of  expansion  sometimes  used.  See  Fig.  23a. 
This  explanation  is  necessary  in  order  to  indicate  why  the 
rectangular  hyperbola  is  taken  as  the  basis  of  such  argu- 
ment as  is  here  offered  about  combined  indicator  diagrams. 

It  is  evident  that,  at  the  point  K' ,  the  exhaust  in  the 
1.  p.  cylinder,  all  of  the  steam  is  not  sent  in  the  1.  p. 
-cylinder  or  receiver,  but  some  of  it  is  retained  and  is  com- 
pressed in  the  clearance  spaces  ;  therefore,  by  calculating 
;the  amount  of  steam  retained,  say  at  q,  we  shall  find  a 


COMPOUND    LOCOMOTIVES. 


- 

N      P" 

6  B 


2 

to 

etf 

Q 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    51 


substantial  amount  to  be  deducted  from  the  amount  at  K' , 
in  order  to  get  the  weight  of  steam  that  is  discharged  into 
the  receiver. 

The  actual  weight  of  steam  used  per  stroke  is  greater 
than  the  apparent  weight,  for  the  reason  that  the  1 5  to  40 
per  cent,  of  the  entering  steam  that  is  condensed  before 
cut-off  is  not  re-evaporated  during  expansion,  and  the 
steam  at  K'  contains  a  large  amount  of  water,  69-72. 

29.  Location  of  Rectangular  Hyperbola  for  Refer- 
ence.— The  point  from  which  the  hyperbola  m  n  should  be 


FIG.  23b. 
Weight  of  Steam  in  Cylinder  at  Different  Points  of  the  Stroke. 

drawn  depends  upon  the  purpose  for  which  the  examina- 
tion is  being  conducted.  Before  further  explanation  of  this, 
it  is  necessary  to  understand  how  much  steam  is  used  in  a 
cylinder  per  stroke,  and  what  should  be  expected  of  it  in  a 
comparatively  perfect  engine,  41-44. 

30.  Weight  of  Steam  Used  per  Stroke. — By  means 
of  the  total  volume  of  the  cylinder  at  any  point,  /£,  Fig.  23, 
which  will  be  represented  by/'  k  and  from  the  pressure  of 
the  steam  represented  by  o'  k,  the  total  weight  of  the  steam 
in  the  cylinder  at  k  can  be  calculated.  This  is  true  of 
other  points,  k'  k' '  and  k' '  ' ,  also  of  q  and  R.  In  a  single  ex- 
pansion engine  it  will  be  found,  by  calculation  from  an  actual 


52  COMPOUND    LOCOMOTIVES. 

indicator  card,  that  the  weight  of  steam  increases  from  k  to 
k' '  '  almost  uniformly,  see  Fig.  230,  42-44.  This  is  due 
to  the  re-evaporation  during  expansion  of  the  steam  that 
was  condensed  before  cut-off,  due  to  the  cooling  effect  of 
the  cylinder  walls.  The  re-evaporation  is  caused  by  the 
heating  effect  of  the  cylinder  walls  on  the  steam  and  water 
in  the  cylinder.  As  the  pressure  falls  during  expansion,  the 
temperature  of  the  steam  falls,  and  the  walls,  being  hotter 
than  the  steam,  re-evaporate  some  of  the  moisture  in  the 
cylinder,  69-72, 

We  have  seen  that  the  steam  sent  to  the  1.  p.  cylinder 
from  the  h.  p.  is  the  difference  between  that  at  k'  and  q. 
If  none  of  this  steam  is  lost  in  transit  through  the  receiver 
or  in  entering  the  1.  p.  cylinder,  it  will  be  apparent  in  that 
cylinder,  and  the  difference  between  the  steam  at  k' '  and 
the  steam  at  R  should  equal  that  sent  from  the  h.  p. 
cylinder.  Later  on,  at /£''',  it  should  be  expected  that 
further  re-evaporation  would  make  more  steam  apparent. 
This  can  be  learned  from  the  difference  between  that  at 
k' ' '  and  R  than  that  between  k' '  and  R.  This  continued 
re-evaporation  in  the  1.  p.  cylinder  generally  takes  place, 
and  in  a  good  compound  locomotive,  where  the  valves  are 
tight,  it  will  be  found  that  the  steam  present,  as  shown  by 
the  indicator  cards,  will  increase  quite  regularly  from  the 
point  k  to  the  point  k'  ' ',  when  allowance  is  made  for  the 
steam  retained  in  the  h.  p.  cylinder  at  q,  44 

31.  Weight  of  Steam  Retained  in  Cylinder  at  End 
of  Compression. — In  assuming  or  locating  the  points  q 
and  R,  much  care  should  be  taken,  as  the  amount  of  steam 
in  the  cylinders,  shown  by  the  indicator  cards,  decreases 
continually  from  the  time  the  exhaust  closes,  which  is  the 
commencement  of  compression,  to  the  opening  of  the  valve 
for  pre-admission  due  to  lead,  6.  The  point  q  should  be 
taken  to  represent,  as  nearly  as  possible,  the  weight  of 
steam  in  the  cylinder  when  the  valve  opens,  and,  there- 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    53 

fore,  it  should  be  taken  well  up  on  the  compression  line, 
and  as  near  to  the  point  of  admission  as  possible.  This  is 
also  true  of  the  point  R.  Fig.  2$b  further  illustrates  this, 
and  shows  the  change  in  apparent  steam  weight  during 
compression.  See  Fig.  4. 

It  is  clear  that  if  the  valves  of  a  compound  engine  are 
tight,  the  same  amount  of  water,  in  the  shape  of  moisture, 
steam  and  water,  must  be  discharged  from  the  h.  p.  as  from 
the  1.  p.  cylinder  at  each  stroke  ;  otherwise,  if  the  1.  p.  dis- 
charged more  than  the  h.  p.  the  receiver  would  be  quickly 
emptied,  or  if  less  than  the  h.  p.  it  would  be  quickly  filled 
with  water  and  steam,  44.  All  this  adjusts  itself  automatic- 
ally, and  the  pressure  in  the  receiver  rises  and  falls  as  the 
cut-offs  in  the  cylinders  are  changed  in  such  a  way  as  to  bring 
about  the  same  discharge  of  water,  in  the  shape  of  steam 
and  moisture,  from  the  1.  p.  cylinder  as  is  discharged  from 
the  h.  p.  cylinder  into  the  receiver. 

32.  Limitations  of  Combined  Diagrams. — In  making 
an  examination  of  the  action  of  an  engine,  by  means  of 
the  combined  diagram,  it  must  not  be  forgotten  that  such 
diagrams  have  a  distinct  limitation,  which  is  found  in  the 
fact  that  they  show  only  the  steam  in  the  cylinder  and, 
therefore,  only  the  apparent  amount  of  water,  and  do 
not  show  the  moisture  or  water  in  the  cylinder,  which 
must  be  added  to  the  apparent  amount  of  water,  in  the 
shape  of  steam,  in  order  to  get  the  actual  total  water 
used  per  stroke,  69-72.  In  other  words,  there  is  a  con- 
siderable amount  of  water  passing  through  the  cylinders 
of  the  compound  engine,  in  the  shape  of  moisture  in  the 
steam,  which  is  not  measured,  indicated  or  made  appar- 
ent by  the  indicator  cards,  69.  However,  this  limitation  of 
the  value  of  combined  diagrams  does  not  prevent  them 
from  being  decidedly  useful  when  such  limitation  is  under- 
stood and  allowed  for,  as  will  appear  from  what  follows : 


54  COMPOUND     LOCOMOTIVES 

33.  Re-evaporation  in  Receiver. —  If  in  a  compound 
receiver  engine  it  is  found  by  calculation  from  the  indicator 
cards,  30,  72,  that  more  apparent  water,    in  the   shape   of 
steam,  is  used  per  stroke  in  the  1.  p.  cylinder   than  in  the 
h.    p.,   then   one  may   be  led  to  understand  that   there   is 
either    a    leakage    in  the  valves  or  a  re-evaporation    (not 
super-heating)  in  the  receiver. 

Super-heating  in  the  receiver  of  a  compound  locomotive 
is  practically  impossible,  unless  the  smoke  box  temperature 
is  above  what  it  should  be  for  good  economy  in  the  boiler, 
for  the  reason  that  the  steam  passes  through  the  receiver 
when  the  engine  is  at  speed  at  a  rate  that  would  make  it 
impossible  to  collect  enough  heat  to  re-evaporate  all  of  the 
moisture  in  the  steam,  much  less  to  cause  a  super-heat, 
54-55.  This  has  been  shown  by  tests  made  by  Mr. 
William  Forsyth,  Mechanical  Engineer,  of  the  Chicago, 
Burlington  and  Quincy  Railroad,  on  a  two-cylinder  com- 
pound locomotive  having  a  receiver  in  the  smoke  box. 
1 1  is  true  that  the  temperature  of  the  smoke  box  is  about  600 
degrees  Fahrenheit,  quite  sufficient  to  produce  a  substantial 
super-heat,  if  the  steam  remained  in  the  receiver  long  enough 
to  permit  it  ;  but  at  200  revolutions  per  minute,  which  is  an 
ordinary  velocity  for  a  locomotive,  there  are  400  exhausts 
into  the  receiver  per  minute.  If  the  receiver  is  about  twice 
the  volume  of  the  1.  p.  cylinder  up  to  cut-off,  then  each 
cubic  foot  of  steam  remains  in  the  receiver  about  Yinr  Pai"t 
of  a  minute,  or  about  ^  of  a  second,  a  much  too  short  time 
to  permit  of  super-heat. 

34.  Condensation  in    Receiver. — On  the  other  hand, 
if  it  is  found  that  less  steam  is  apparently  used  in  the  1.  p. 
cylinder  than  is  discharged  into  it  from  the  h.  p.  cylinder 
per  stroke,  then  it  may  be  expected  that  there  is  a  loss'  of 
steam    by    condensation    in    the   receiver    or   in    the    1.    p. 
cylinder,   54—55.     Some  results  of  calculation  of  this  kind 
are  given  in  Table  J.     30,  72. 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    55 

In  this  way  an  examination  can  be  made  to  learn  if  the 
steam  at  k' ' ,  Fig.  23,  less  that  at  R,  is  greater  than  that  at 
k' ' ,  less  that  at  q.  This  will  indicate  whether  there  is  a  gain 
or  loss  up  to  cut-off  in  the  1.  p.  cylinder.  Allowance  should, 
of  course,  always  be  made  for  the  steam  at  q  and  R,  as  the 
steam  at  R  always  mixes  with  the  incoming  steam  from  the 
h.  p.  cylinder.  To  be  still  more  accurate,  the  difference  in 
the  heat  contained  per  pound  of  the  steam  at  R,  q,  k' ' ,  and 
k' ,  should  be  allowed  for. 

35.  What  is  Shown  by  Reference  Curve  on  Com- 
bined Diagrams. — It  now  will  be  clear  that  in  drawing  the 
rectangular  hyperbola  m  n,  it  may  be  drawn  from  the  point 
k  to  note  the  re-evaporation  at  k' ,  or  from  some  point,  as  m, 
located  so  that  the  volume  P  m  corresponds  to  the  volume 
of   the  weight  of  the  steam,  which  is   discharged  into  the 
1.  p.  cylinder   at  each  stroke.      Manifestly,  when  the  curve 
m  n  is  located  in  this  way,  it  will  fall  to  the  left  of  k' ,  Fig. 
23,  and  if  there  is  no  loss  between  the  cylinders  and  up  to 
cut-off  in  the   1.  p.  cylinder,   it  will   pass  just  to  the  left  of 
point  k' '    and   inside   of  the   expansion   curve   of  the  1.  p. 
cylinder  by  an  amount  which  depends  upon  the  steam  that 
is  added   to  the   incoming   steam   from  the   h.  p.  cylinder, 
from    the    compression    or    clearance    spaces    in    the   1.   p. 
cylinder.     This  last  amount  is  that  which  is  calculated  for 
the   point  R.     This  is  further  explained   in  the  analysis   of 
the  combined  diagrams  from  the  four-cylinder  non-receiver 
type,  41-44. 

36.  Ideal    Combined    Diagram. — To  show  what  the 
ideal  combined   indicator  card  would  be  from  a  compound, 
reference    is    made    to    Fig.    24.       This    card    was    taken 
from   a  triple   expansion   Corliss  pumping   engine  running 
at   twenty    revolutions   per    minute.       The    cylinders  were 
5   feet   stroke,  and  with  the   following    diameters:     H.  p. 
cylinder,    28    inches ;     intermediate    cylinder,    48    inches  ; 
1.   p.  cylinder,    74    inches.      Careful    tests    of    this    engine 


56  COMPOUND    LOCOMOTIVES. 

showed  a  consumption  of  twelve  pounds  water  per  horse- 
power per  hour.  There  is  little,  if  any,  loss  of  steam  by  the 
drop  in  the  receiver,  and  practically  no  loss  from  com- 
pression and  wire-drawing.  Compound  locomotives  cannot 
be  made  to  give  cards  like  this,  even  at  the  slowest  speed,, 
for  the  reason  that  the  locomotive  has  to  be  designed  to 
work  at  different  cut-offs,  while  the  stationary  compound  is 
made  principally  for  a  single  cut-off,  or  with  very  small 
variations  therefrom.  However,  a  comparison  of  this 
card  with  an  actual  indicator  card,  Fig.  25,  will  show 
where  the  loss  occurs  in  the  compound  locomotive  at  the 


FIG.  24. 
Ideal  Combined  Card. 

present  time,  and  further  explains  why  high  speed  com- 
pound locomotives  have  not  given  the  economy  that  they 
should,  139-147. 

The  upper  cards  A  and  B  of  this  diagram,  Fig.  24,  rep- 
resent probably  the  best  steam  distribution  that  has  been 
obtained  from  a  two-cylinder  receiver  compound.  Taking 
the  area  of  these  cards  A  and  B  and  calculating  the  horse 
power,  omitting  the  1.  p.  card  C,  and  taking  the  same  total 
water  per  hour  that  was  actually  used  in  the  test,  the  water 
per  horse  power  is  found  to  be  18  pounds.  That  is  to  say, 
wrhile  the  water  per  horse  power  per  hour  with  the  triple 
expansion  engine,  giving  cards  A,  B  and  C,  is  12  pounds, 
yet  by  omitting  the  work  done  by  card  C,  to  bring  the 
result  more  nearly  like  a  two-cylinder  compound  locomo- 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    57 

tive,.  the  resulting  water  per  horse  power  per  hour  is  about 
1 8  pounds.  It  may  be  said  then  that  a  compound  locomo- 
tive must  use  steam  with  approximately  as  good  distribution 
as  shown  by  Fig.  24,  in  order  to  reach  as  low  a  water  rate 
as  1 8  pounds  per  horse  power  per  hour.  However,  the 
steam  pressure  on  a  locomotive  is  generally  higher,  say  180 
pounds  per  square  inch,  while  in  the  case  of  Fig.  24  the 
steam  pressure  was  but  120  pounds.  On  the  other  hand, 
the  triple  expansion  engine  had  steam  jackets  and  other 
advantages  which  would  tend  to  offset  the  advantage  of 
higher  boiler  pressure. 


FIG.  25. 

Actual  Combined  Card. 

37.  Combined  Diagram  from  Non- Receiver  or 
Woolf  Type.  —  Combined  diagrams  from  the  Woolf  type 
of  compound  having  no  receiver,  sometimes  called  "  con- 
tinuous expansion  "  compounds,  differ  greatly  in  appear- 
ance from  those  of  receiver  compounds,  27—32,  as  will 
appear  from  Figs.  23  and  26.  The  following  is  an  analysis 
of  Fig.  26,  which  will  emphasize  what  has  been  said  about 
steam  use  for  Fig.  23.  The  cards  in  Fig.  26  have  been 
combined  on  a  new  plan,  which  shows  the  effect  of 
clearance  in  the  cylinders  and  valves.  The  line  ZC' '  is. 


58  COMPOUND    LOCOMOTIVES, 

the  line  of  zero  pressure.  The  line  of  atmospheric  pressure 
is  just  above  it.  The  mean  effective  pressures  and  the 
clearances  of  the  engine  are  given  on  the  diagram.  The 
indicator  cards,  shown  on  the  left  hand  part  of  the  diagram, 
are  an  exact  reproduction  of  the  ones  taken  from  the 
engine.  The  indicator  diagram  on  the  right  side  shows  the 
1.  p.  diagram  enlarged,  so  that  the  pressure  at  each 
individual  point  of  the  diagram  is  plotted  on  a  volume 
exactly  equal  to  the  volume  which  the  steam  occupied  in 
the  1.  p.  cylinder  when  it  had  a  corresponding  pressure. 
For  instance,  take,  the  point  K  on  the  1.  p.  diagram,  the 
pressure  represented  by  G'  K  is  exactly  that  which  was 
in  the  1.  p.  cylinder  at  admission,  and  is  equal  to  F'  Y, 
while  the  volume  which  is  represented  by  the  distance  0  G' , 
is  exactly  the  volume  which  the  steam  occupied  in  the 
cylinders  when  it  has  the  pressure,  G'  K,  and  this  is  true 
of  every  other  point  on  the  expansion  line  of  the  combined 
diagram. 

38.  Method  of  Combining  Indicator  Cards  from 
Non-Receiver  Type. — The  method  of  combining  the 
diagrams  is  as  follows  : 

From  0,  which  is  the  point  of  zero  volume,  the  distance 
0  C'  is  laid  off  equal  to  the  h.  p.  clearance.  C'  F'  is  the 
length  of  the  indicator  card  as  taken.  F'  P'  corresponds 
to  the  volume  of  the  space  in  the  valve  between  the  h.  p. 
and  the  1.  p.  cylinders.  P!  G'  corresponds  to  the  clearance 
in  the  1.  p.  cylinder.  OC"  corresponds  to  the  volume  of 
the  1.  p.  cylinder  (being  about  2.93  times  the  volume  of  the 
h.  p.  cylinder),  plus  the  1.  p.  clearance.  Between  the 
vertical  lines  drawn  from  C'  F'  the  actual  indicator  card 
is  laid  out. 

The  line  K  H  is  the  expansion  line  in  the  1.  p.  cylinder 
taken  from  the  actual  indicator  card,  and  the  pressure  at 
every  point  on  this  expansion  line  is  plotted  at  a  volume 
point  exactly  corresponding  to  the  volume  of  the  steam  in 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    59 

the  cylinders,  as  shown  by  the  actual  indicator  cards.  At 
the  point  //,  which  is  the  cut-off  in  the  1.  p.  cylinder,  the 
volume  is  reduced  by  the  amount  HJ,  which  is  the  sum  of 
the  volume  of  the  interior  of  the  valve,  or  R  Q,  and  the 
volume  remaining  in  the  h.  p.  cylinder  and  the  volume  of 
h.  p.  cylinder  clearance  together,  or  V  U.  Thus  the  volume 
occupied  by  the  steam  after  cut-off  is  represented  by  the 
distance  0  M' ,  and  the  pressure  corresponding  to  that 
volume  is  M'  J. 

After  cut-off  the  steam  expands  from  the  point  /,  as 
shown  by  the  line//',  and  this  line  corresponds  with  the 
expansion  line  on  the  actual  indicator  card ;  that  is,  at  each 
point  the  pressure  is  plotted  on  a  volume  corresponding  to 
the  actual  volume  occupied  by  the  steam. 

This  method  of  plotting  is  necessary  in  order  that  a 
comparison  may  be  made  between  the  lines  EE' -££" -DD' 
and  D  D" ,  which  are  theoretical  lines  drawn  to  show  any 
peculiarities  of  the  expansion  of  the  steam  in  the  two 
cylinders,  43.  Without  this  method  of  plotting  no  fair 
comparison  could  be  made,  as  the  pressure  would  not  be 
plotted  on  actual  volumes,  and  a  false  and  untrue  condition 
would  be  exhibited. 

The  over-lapping  of  the  1.  p.  indicator  card  from  H  to 
J  is  necessary  by  reason  of  the  abrupt  reduction  in  the 
volume  occupied  by  the  steam  at  cut-off  in  the  1.  p.  cylinder, 
the  reduction  being  caused  by  the  cutting  out  of  the  volume 
of  the  valve  and  the  volume  yet  remaining  before  the  com- 
pletion of  the  stroke  of  the  h.  p.  cylinder.  In  order  that 
the  true  area  of  the  combined  indicator  card  may  be  pre- 
served, it  has  been  found  convenient  to  draw  the  dotted 
sections  R  Q  P  S  and  V  U  T  W,  which  are  together  equiv- 
alent to  JIN  M.  This  makes  the  mean  effective  pressure 
determined  from  the  entire  area  of  the  combined  indicator 
cards,  including  the  dotted  section,  exactly  the  same  as 
that  determined  from  the  original  cards. 


6o 


COMPOUND    LOCOMOTIVES. 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    6  I 

The  pressure  during  exhaust  and  compression  on  the 
combined  diagram  is  plotted  at  the  same  point  as  the  cor- 
responding pressure  in  the  steam  line  of  the  actual  card  ; 
that  is  to  say,  the  back  pressure  at  N  is  the  one  correspond- 
ing to  the  back  pressure  on  the  point  below  the  cut-off 
point  on  the  original  indicator  card.  That  is,  the  pressure 
at  N  is  the  same  as  the  pressure  at  U,  just  as  the  pressure 
at  H  is  the  same  as  the  pressure  at  T.  This  is  an  unim- 
portant fact,  however,  as  the  combined  diagram  is  mainly 
drawn  for  the  purpose  of  examining  the  correspondence 
between  the  theoretical  expansion  line  and  the  actual  ex- 
pansion line  of  the  steam  in  the  cylinders,  and  not  to  get 
the  mean  effective  pressures.  By  these  lines  are  shown  the 
continual  re-evaporation  and  corresponding  increase  in  ap- 
parent steam  weight  during  expansion  in  the  h.  p.  cylinder. 
At  the  point  3  the  h.  p.  cylinder  exhausts  into  the  valve  and 
into  the  1.  p.  cylinder  clearance.  Here  it  meets  with  steam 
that  was  retained  in  the  valve  at  cut-off  at  the  point  H  or 
T  in  the  1.  p.  cylinder,  and  with  steam  that  was  left  in  1.  p. 
cylinder  clearance  after  compression,  and  therefore  the 
total  steam  weight  is  increased. 

If  no  steam  leaked  out  of  the  valve  or  condensed  from 
the  time  it  was  shut  in  at  cut-off  in  the  1.  p.  cylinder,  and 
none  of  the  steam  was  condensed  or  lost  from  the  clearance 
spaces  after  compression  in  the  1.  p.  cylinder,  the  total 
steam  weight  at  the  point  K  would  be  the  sum  of  the  steam 
exhausted  from  the  h.  p.  cylinder,  the  steam  that  was  left 
in  the  valve,  and  the  steam  remaining  in  the  1.  p.  clearance. 
39.  Losses  Shown  by  Combined  Diagram  from 
Non-Receiver  Type. — If  there  were  no  losses,  and  making 
due  allowance  for  the  lower  pressure  arid  temperature  of 
the  steam  in  the  valve  and  in  the  1.  p.  clearance,  the  pres- 
sure at  K,  Fig.  26,  should  be  101  pounds  absolute  instead 
of  92  pounds.  The  weight  of  the  steam  in  the  valve  and 
in  the  1.  p.  clearance,  which  would  be  mixed  with  the  steam 


62  COMPOUND    LOCOMOTIVES. 

from  the  h.  p.  cylinder,  at  exhaust  from  the  h.  p.  cylinder 
is  about  21  y2  per  cent,  of  the  weight  exhausted  from  the 
h.  p.  cylinder,  provided  there  was  no  loss  of  any  kind  from 
the  clearance  of  the  1.  p.  cylinder  and  the  clearance  in  the 
valve  after  the  steam  wras  shut  into  these  cavities.  The 
point  G  shows  what  the  pressure  would  be  if  there  was  no 
loss.  If  all  the  steam  shut  in  was  lost,  then  the  point  K 
would  fall  about  to  the  point  Y'.  The  tighter  the  valve 
and  the  less  the  loss  in  other  ways  of  the  steam  that  is  shut 
in,  the  higher  the  point  A"  will  be  above  the  point  Y'.  It 
has  been  said  that  the  rise  of  pressure  at  the  point  K  above 
Y'  shows  leakage,  but  this  is  a  mistake,  unless  all  the 
steam  shut  into  the  valve  and  into  the  1.  p.  clearance  is 
assumed  to  be  lost.  That  this  steam  is  not  wholly  lost  is 
shown  by  the  fact  that  the  point  K  does  actually  rise  con- 
siderably above  the  point  Y'. 

As  we  go  on  with  this  analysis  to  the  pomt  of  cut-off, 
or  at  //,  we  find  that  the  weight  of  steam  in  the  cylinders, 
as  shown  by  the  indicator  card,  increases  continuously  and 
according  to  the  following  numbers  : 

Weight  at  K,  .66  pounds  ;  and  at  other  points,  .66,  .68 
and  at  the  point  H  .70  pounds.  At  this  point  the  volume 
is  decreased  by  H  J,  and  steam  at  the  pressure  H  is  shut 
into  the  valve  and  the  h.  p.  cylinder,  and  the  total  apparent 
steam  weight  is  decreased,  as  shown  by  the  actual  indicator 
card,  to  .575  pounds,  the  pressure,  of  course,  remaining 
the  same  as  at  H. 

In  the  case  of  this  particular  indicator  card,  it  is  curious 
to  note  that  the  point  /  falls  upon  the  hyperbola  E  Y' 
E'  drawn  from  the  h.  p.  indicator  card  expansion  line,  and 
indicates  that,  up  to  the  point  of  cut-off  in  the  1.  p. 
cylinder,  there  has  not  been  leakage  enough  or  re-evapora- 
tion enough  to  raise  the  steam  pressure  above  the  hyperbola 
drawn  from  the  expansion  line  of  the  h.  p.  indicator  card. 

Also  it  is  a  curious  fact  that  in  this  particular  indicator 


COMBINED   INDICATOR  CARDS — WEIGHT  OF  STEAM.    63 

card  the  expansion  line  in  the  1  p.  cylinder  after  cut-off,  as 
shown  by  /  /,  corresponds  almost  exactly  with  the  hyperbola 
E  E' ,  just  described.  This  shows  that  while  at  the  point  of 
the  exhaust  from  the  h.  p.  cylinder  a  considerable  amount 
of  steam  is  added  to  that  exhaust  (from  the  interior  of  the 
valve  and  from  the  1.  p.  clearance),  yet  this  added  steam 
is  not  wholly  lost,  but  part  is  returned  again  to  the  valve  and 
h.  p.  cylinder  at  the  point  of  cut-off  in  the  1.  p.  cylinder. 

As  has  been  said  before,  28,  the  hyperbola  corresponds 
more  nearly  to  the  actual  expansion  line  of  steam  in  a 
locomotive  cylinder  than  does  the  adiabatic,  owing  to  the 
re-evaporation  of  the  steam  that  was  condensed  up  to 
the  point  of  cut-off.  Therefore,  if  the  pointy  on  any  com- 
bined indicator  card  should  fail  much  below  the  hyperbola 
E  E' ,  one  would  suspect  considerable  loss  due  to  condensa- 
tion ;  and  if  it  should' rise  very  much  above  this  hyperbola, 
one  would  suspect  leakage  or  an  unusual  amount  of  re- 
evaporation,  but  more  probably  leakage. 

40.  Correct  Area  of  Combined  Diagram  Non- 
Receiver  Type.  —  In  measuring  the  area  of  this  combined 
indicator  card,  one  must  follow  the  lines  K  H  IE"  N  M  L 
K.  This  will  appear  from  a  study  of  the  way  in  which  the 
card  is  laid  out.  This  method  of  combining  cards  is  ex- 
ceedingly simple  and  can  be  followed  without  incon- 
venience. To  do  it  one  needs  only  to  calculate  the  volume 
occupied  by  the  steam  at  several  points  and  plot  these  vol- 
umes from  0  as  an  origin. 

41.  Reference  Curve  for  Combined  Diagram  Non- 
Receiver  Type. — The  proper  theoretical  line  to  be  drawn 
for  comparison  on  a  combined  indicator  card  is  a  matter  of 
some  dispute,  but  as  each  line  has  its  own  particular  value 
and  meaning,  there  is  not  much  to  dispute  about,  43.  The 
point  from  which  the  theoretical  line  should  be  drawn  is  of 
more  importance. 

In  a  single  expansion  engine  with  tight  valves,  the  total 


64  COMPOUND    LOCOMOTIVES. 

.amount  of  water  in  the  shape  of  steam  and  moisture  in  the 
cylinder  does  not  change  after  cut-off  until  exhaust  is 
reached.  Some  of  the  steam  may  be  condensed,  but  the 
total  water  remains  the  same.  With  compound  engines,  of 
the  non-receiver  type,  however,  this  is  not  so,  for  the  reason 
that  at  cut-off  in  the  h.  p.  cylinder  and  at  the  closure  of  the 
exhaust  from  the  h.  p.  cylinder,  a  considerable  amount  of 
: steam  is  retained  in  the  valve  and  clearance  of  the  h.  p. 
cylinder.  The  steam  used  per  stroke  in  the  h.  p.  cylinder, 
as  apparent  from  the  indicator  card,  is  the  difference  between 
the  amount  present  in  the  cylinder  at  the  point  3,  Fig.  26  ; 
and  the  amount  retained  in  the  cylinder  during  compression, 
.taken  for  example  at  the  point  4.  For  one  to  draw  the 
theoretical  steam  line  from  the  point  3  is  to  assume  that  all 
the  steam  that  enters  the  h.  p.  cylinder  during  admission  is 
exhausted  therefrom,  but  this  is  not  true.  The  real  amount 
is  the  difference  just  referred  to,  and  is  represented  by  the 
volume  B  D,  B  E  being  the  amount  admitted  to  the  h.  p. 
cylinder;  so  that  to  look  for  leakage  or  re-evaporation  in 
the  1.  p.  cylinder  after  cut-off,  the  theoretical  steam  line 
should  be  drawn  from  the  point  D,  and  not  from  the 
point  E, 

42.  Weight  of  Steam  per  Stroke.  —  It  may  not  be 
clear  why  this  is  so  without  further  explanation.  In  any 
compound  engine  as  much  water  in  the  shape  of  steam  or 
moisture  must  pass  out  of  the  1.  p.  cylinder  as  is  passed  out 
of  the  h.  p.  cylinder ;  otherwise,  there  will  be  a  collection 
of  water  in  the  1.  p.  cylinder  which  would  go  on  until  the 
cylinders  were  full.  That  is,  the  amount  of  water  in  the 
shape  of  steam  taken  from  the  boiler  at  each  stroke  of  the 
h.  p.  cylinder  must  be  the  same  as  that  thrown  out  from 
the  1.  p.  cylinder  at  each  stroke. 

If  the  volume  B  D  and  pressure  at  D  indicates  the 
amount  of  steam  given  from  the  h.  p.  cylinder  to  the  1.  p. 
,at  each  stroke,  then  this  amount  should  be  looked  for  after 


COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    65 

the  cut-off  in  the  1.  p.  cylinder,  barring,  of  course,  all  gains 
due  to  re-  evaporation  of  the  moisture  in  the  steam  and  the 
losses  due  to  any  condensation,  69,  that  may  take  place. 
This  leads  to  the  conclusion  that  in  an  examination  of  the 
steam  lines  on  the  combined  card  from  E  to  H  (H  being 
the  point  of  cut-off  in  the  1.  p.  cylinder,  and  also  the  point 
of  the  commencement  of  compression  in  the  h.  p.  cylinder), 
the  theoretical  expansion  line  should  be  drawn  from  the 
point  E  and  for  the  examination  of  the  steam  pressures  after 
cut-off  in  the  1.  p.  cylinder,  that  is,  from /to  the  end  of  the 
stroke,  the  theoretical  steam  line  should  be  drawn  from  the 
point  D.  It  follows,  then,  that  to  determine,  by  compari- 
son of  pressures  at  the  end  of  the  expansion  of  steam  in 
the  two  cylinders,  the  leakage,  re-evaporation,  or  con- 
densation, during  the  passage  of  the  steam  through  the 
cylinders,  the  theoretical  steam  line  should  be  drawn  from 
the  point  D  and  the  comparisons  should  be  made  after 
cut-off  in  thel.  p.  cylinders.  This  is  because  any  leakage, 
re-evaporation,  or  condensation,  will  show  up  most  prom- 
inently after  the  cut-off  point/,  Fig.  26. 

43.  Other  Reference  Curves  for  Combined  Dia- 
grams.—  In  this  particular  diagram  both  the  hyperbola 
and  the  adiabatic  lines  have  been  drawn  from  both  points 
E  and  D.  E  E'  and  D  D'  are  hyperbolas,  E  E"  and  D 
D"  are  adiabatic  curves.  It  will  be  seen  that  the  point  / 
rises  considerably  above  the  adiabatic  curve  drawn  from  D, 
and  this  shows  either  some  leakage  or  re-evaporation.  It 
also  falls  somewhat  above  the  hyperbola  from  the  point  D. 
This  is  a  further  indication  of  leakage  or  re-evaporation  ; 
but  there  is  and  should  be  in  every  engine  a  considerable 
amount  of  re-evaporation,  which  will  frequently  raise  the 
actual  steam  line  above  the  hyperbola.  Therefore,  so  far 
as  this  combined  diagram  shows,  there  is  no  strong  evidence 
of  leakage.  However,  the  combined  diagram  is  not  the 
best  way  to  show  leakage.  It  is  a  good  graphical  way  of 


66 


COMPOUND    LOCOMOTIVES. 


showing  how  the  volume,  pressure  and  weight  of  steam 
changes  during  the  entire  expansion  of  the  steam,  but  it  is 
not  as  accurate  in  showing  leakage  or  re-evaporation  as  the 
comparison  of  the  steam  weights.  See  Appendix  O. 

44.  Weight  of  Steam  per  Stroke,  Various  Com- 
pound Locomotives. — Take  this  particular  card  and  refer 
to  Table  J,  Card  No.  3,  C.  B.  &  Q.  tests.  It  will  be  seen 
that  the  card  shows  that  .507  pounds  of  steam  was  used  per 
stroke  in  the  h.  p.  cylinder  and  .493  pounds  used  per  stroke 
in  the  1.  p.  cylinder.  These  amounts  are  practically  the 
same,  and,  so  far  as  the  indicator  card  goes,  there  is  no 
evidence  of  more  steam  being  thrown  out  of  the  1.  p. 

TABLE   J. 

Giving  the  Weight  of  Steam  Used  per  Stroke  in  Several  Compound  Locomo- 
tives.     This  Data  was  Calculated  from  Sample  Indicator  Cards. 


S 

g    «U 

Jc  ci 

c"o  A 

d. 

•E 

c3 

a 

4)   O 
"IS 

u  o 

•St: 
£  c 

.5°  • 
£  c 

"°  « 
^^  js  _; 

*'  g  « 

Engine. 

o 

C   U 

°  aE- 

1  a"& 

si 

£e 

a  « 

g  w 

c 

«  o.'S 

rt 

*a  3 

.c 

«  « 

8 

^  S 

fc^     W!       • 

rt  rt    • 

os  oj 

*?      •"  rL 

1 

JN 

?" 

1^ 

J3°fr 

Q^" 

^His^ 

(gSS& 

§** 

51 

121.4 

.4999 

.5026 

.0027 

0.5 

67 

Baldwin    No.    82    in 
C.,  B.  &  Q.  tests. 

48 
8 
3 

140.1 

210.2 
I40.I 

.5000 
.3428 
•5071 

•4931 
.3650 
.4908 

.0222 

.0069 
.0163 

"6.'5" 

1.4 
3.2 

g 

33 

186.8 

.3780 

.4052 

.0272 



7-2 

58 

i 

120 

.4568 

•4451 



.0117 

2-5 

58 

Baldwin    No.    82    in 
Erie  tests. 

2 

3 
4 

160 
160 
140 

.4320 
.4293 
•3499 

•4452 
.4007 
'3564 

.0132 
.0065 

'.0286 

3.0 
1.9 

'  '  '6.6  '  ' 

48 

5 

172 

.3605 

.3681 

.0076 

2.1 

52 

Schenectady,  12 
Wheeler, 

2&2a 
6&6a 

15° 
156 
1  80 

.8022 
I-J374 

•7I03 
1.0646 

.0919 
.0928 

11.46 

8.02 

44 
66 

Eng.  No.  367. 

8&8a 

192 

.9518 

•8579 



•°939 

9.86 

Schenectady,  10 

61 

100 

.7920 

.7144 



.0776 

9.80 

59 

Wheeler, 

74 

152 

.7028 

-6363 



.0665 

9.46 

59 

Mich.  Cent. 

80 

124 

.8247 

•7259 

.0988 

11.98 

59 

C.,  B.  &  Q.  Mogul, 
Eng.  No.  324. 

8 
49 

243.9 

.5861 
.4932 

.6631 
.6001 

.0770 
.1069 

21.6 

:::::::: 

35 

Rhode  Island  Comp. 
on   Brooklyn   Ele- 

27 

1  80 

006 

.2765 

.2639 



.0126 

4.0 

86 
64. 

vated. 

Great  Eastern  Wors- 

3 

252 

.5110 

.4586 

.0524 

10. 

42 

dell    Comp.,    Eng. 

4 

192 

•4992 

.4609 

-0383 

7-7 

57 

No.  230. 

5 

264 

.3918 

•3390 

.0528 

13-5 

48 

X 

72 

•593° 

.6918 

.0988 

16.6 

69 

TVIpvi      n    (~*pnf«.o1 

60 

6611 

0664 

Johnstone  Comp. 

3 

57 

•6344 

.7140 

.0796 

12.5 

79 

4 

66 

•5887 

•6399 

.0512 



8-7 

70 

COMBINED  INDICATOR  CARDS WEIGHT  OF  STEAM.    6/ 

cylinder  than  is  thrown  out  of  the  h.  p.  cylinder,  which 
would  be  the  case  if  there  was  any  considerable  leakage 
through  the  piston  valve.  In  making  these  analyses  one 
must  remember  that  there  is  a  large  amount,  something 
over  30  per  cent.,  of  water  present  in  the  steam  at  the  point 
of  cut-off  in  the  h.  p.  cylinder,  and  the  major  part  of  this 
water  goes  through  the  engines  without  being  shown  on 
the  indicator  card.  It  is  this  water  which  re-evaporates 
and  raises  the  steam  line  at  cut-off  in  the  1.  p.  cylinder 
above  the  adiabatic  curve.  We  have  seen  that  in  this  card 
there  is  no  more  steam  used  by  the  1.  p.  cylinder  than  by 
the  h.  p.,  but  this  is  also  true  of  other  cards  from  this  and 
other  engines  of  the  same  type,  as  shown  by  Table  J. 
As  the  pressure  of  the  steam  decreases  during  expansion 
there  is  a  continual  increase  in  apparent  weight  from  the 
indicator  cards. 

If  the  rate  of  re-evaporation  in  the  h.  p.  cylinder  (if 
such  it  be  and  not  leakage,  and  it  probably  is  re-evapo- 
ration, as  there  is  no  reason  to  believe  that  steam  would 
not  re-evaporate  in  this  type  of  h.  p.  cylinder  just  as  in 
any  other  h.  p.  cylinder)  be  continued  until  the  commence- 
ment of  the  stroke  of  the  1.  p.  cylinder,  the  weight  of 
steam  at  K,  Fig.  26,  would  correspond  to  the  actual  appar- 
ent weight  from  the  indicator  card.  But  it  is  not  to  be 
expected  that  this  rate  of  re-evaporation  would  thus  con- 
tinue, owing  to  the  fact  that  the  steam  when  it  is  dis- 
charged from  the  h.  p.  cylinder  meets  comparatively  cold 
surfaces  and  intermingles  with  steam  in  the  valve  and  in 
the  1.  p.  clearance  which  is  of  a  lower  temperature.  Of 
course  this  last  argument  is  mainly  a  speculation,  and  is 
interesting  only  so  far  as  speculation  goes.  It  is  a  curious 
fact,  however,  that  assuming  the  rate  of  re-evaporation  to 
continue,  the  calculated  weight  of  the  steam  shut  into  the 
valve  and  1.  p.  clearance  would  raise  the  pressure  to  G"  at 
the  commencement  of  the  stroke  of  the  1.  p.  cylinder,  and 


Of  THB    - 

WVBBSXTY 


68  COMPOUND    LOCOMOTIVES. 

the  loss  would  have  been  G"  K,  but  that  it  is  impossible 
that  this  was  the  case  is  clearly  seen  from  an  analysis 
of  the  steam  weight  at  different  points  of  the  indicator 
card.  To  claim  that  the  valve,  at  the  time  of  admission  to 
the  1.  p.  cylinder,  is  filled  to  the  same  pressure  as  the  pres- 
sure of  the  exhaust  from  the  h.  p.  cylinder,  as  has  been 
claimed,  is  to  admit  that  the  area  represented  by  G" K  H 
H'  is  wholly  lost.  But  it  is  easily  shown  that  this  is  not 
the  case.  < 

The  indicator  card,  Fig.  26,  shows  that  about  17.4 
pounds  of  steam  were  used  per  horse-power  per  hour.  Of 
course  this  does  not  account  for  the  loss  due  to  condensa- 
tion up  to  cut-off.  From  the  actual  tests  an  approximate 
estimate  of  the  water  used  per  horse-power  per  hour  is  29.9 
pounds,  leaving  10.5  pounds  of  water  per  horse-power  per 
hour  not  shown  by  the  indicator  card,  the  measurements 
being  taken  just  after  cut-off  in  the  h.  p.  cylinder.  This 
indicates  a  condensation  of  about  37  per  cent,  of  the  steam 
entering  the  h.  p.  cylinder  up  to  cut-off.  The  insufficient 
data  from  which  this  result  is  obtained  renders  it  probable 
that  the  37  per  cent,  is  not  the  correct  amount.  It  may  be 
more,  but  it  is  probably  less.  This,  of  course,  is  only 
another  speculation  and  interesting  only  so  far  as  specu- 
lations go.  However,  the  plan  of  analysis  indicates  what 
can  be  done  when  a  complete  set  of  data  is  furnished. 
Whether  this  data  can  be  collected  from  a  road  test  is 
somewhat  uncertain,  but  it  surely  can  be  collected  from  a 
shop  test,  such  as  is  now  made  regularly  at  the  Purdue 
University  by  Professor  Goss,  who  has  a  large  Schenectady 
single-expansion  eight-wheel  locomotive  mounted  on  carry- 
ing wheels  and  operated  with  as  much  power  as  the  same 
engine  would  exert  if  it  were  hauling  a  regular  train.  The 
advantage  of  this  arrangement  is  that  very  accurate 
measurements  can  be  made  of  the  water  and  fuel  used. 
It  also  permits  accurate  indicator  cards  to  be  taken. 


CHAPTER   VII. 

TOTAL   EXPANSION.      RATIO   OF   CYLINDERS. 

45.  Total    Expansion    from    Elementary    Indicator 
Cards.  —  It    is   frequently    necessary,  for    the   purpose   of 
comparing   the  action   of   locomotives,   to    know  the  total 
expansion  of  the  steam   in  each  type,  and  while  it  might 
appear   from   Figs.  I  and   2,  2—3,  that   this   can  be  done  by 
reasoning   from   the   known  volumes  of  the   cylinders  and 
points  of  cut-off,  yet  in  fact  the  steam  use  is  so  affected  by 
wire-drawing  and  compression  that  calculation  is  of  little  or 
no   value,   12-19.     The  only  accurate  way  to  get  the  total 
expansion  is  to  examine  the  actual  indicator   cards,  from 
a  locomotive  that  has  been  built,  or  the  pre-determined  indi- 
cator cards  of  a  proposed  design.     These  pre-determined 
cards  should  always  be  made  up  from  cards  from  existing  en- 
gines of  similar  design,  with  such  corrections  as  experience 
or  judgment  show  to  be  necessary  to  include  the  differences 
between  the  proposed  and  actual  locomotives.     An  approxi- 
mate method  of  calculating  the  total  expansion  from  the 
elementary  indicator  card  is  given  in  Appendix  D. 

46.  Total  Expansion  from  Actual  Indicator  Cards.— 
The  difference  which   is  generally  found  between  the  theo- 
retical* total  expansion  and  the  actual  total  expansion   in 
practice  is  sh®wn  by  Table  K. 

Table  K,  taken  from  same  data  as  Tables  B,  C,  D,  E,  F, 
and  G,  shows  the  difference  in  the  ratios  of  expansion  in  the 
individual  cylinders  and  the  total  in  both  cylinders  when 
estimated  by  different  rules  commonly  used,  and  illustrates 

*"  Theoretical  "  as  here  used  is  intended  to  be  understood  as  applying  to  the  limited  theory 
of  steam  expansion  commonly  used  as  a  basis  for  the  computation  of  mean  effective  pressures. 
See  Chapter  I. 

69 


COMPOUND    LOCOMOTIVES. 


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TOTAL    EXPANSION RATIO    OF    CYLINDERS.  71 

the  variation  in  the  results  given  by  these  rules,  and 
emphasizes  the  need  of  a  perfect  understanding  of  the  wide 
difference  between  the  theoretical  and  practical  operation 
of  compound  locomotives 

The  important  fact  is  shown  that  the  ratio  of  the  initial 
and  final  volumes  in  nowise  indicates  the  real  ratio  of  ex- 
pansion. This  results  from  the  effect  of  the  comparatively 
small  receivers  used,  which  gives  a  large  drop  in  pressure 
in  the  receiver,  25-26,  and  the  wire-drawing  due  to  in- 
adequate valve  motion.  .  This  more  particularly  applies  to 
the  conditions  when  the  engine  is  running  at  considerable 
speed,  for  at  such  times  the  reduction  of  pressure  due  to 
wire-drawing  is  equal  to  or  greater  than  the  reduction 
resulting  from  expansion.  This  shows  how  a  compound 
locomotive  at  high  speed  may  approach  more  nearly  to  a 
throttle-governed  wire-drawing  steam  engine  than  to  one 
having  a  variable  cut-off.  It  is  this  action  which  reduces 
so  greatly  the  otherwise  possible  saving  of  a  compound 
locomotive  at  high  speed,  139-147,  and  when  taken  to- 
gether with  losses  resulting  from  compression  gives  nearly 
a  full  explanation  of  the  reasons  why  a  majority  of  com- 
pound locomotives,  thus  far,  have  not  shown  a  very  sub- 
stantial saving  in  passenger  service. 

Note. — The  terminal  pressure  for  Table  K  is  not  taken 
as  that  at  exhaust,  but  is  taken  at  an  equated  pressure  lying 
between  that  at  exhaust  and  that  at  the  end  of  the  stroke. 
This  is  done  to  allow  for  the  useful  work  done  by  the  steam 
during  exhaust  before  the  end  of  the  stroke  is  reached. 
The  equated  terminal  pressure  thus  taken  is  not  an  arith- 
metical mean  of  the  pressure  at  exhaust  and  the  pressure 
at  the  end  of  the  stroke,  but  is  so  selected  as  to  allow  for 
the  work  done  from  the  exhaust  point  to  the  end  of  the 
stroke.  For  the  slow-speed  cards  it  is  taken  nearly  at  the 
exhaust  point,  and  for  the  high-speed  cards  nearly  at  the 
end  of  the  stroke. 


72  COMPOUND    LOCOMOTIVES. 

47.  Ratio     of    Cylinders  —  Elementary     Formulas 
for.  —  In    treatises   on    compound    engines,   formulas    have 
been  deduced  for  the  ratio  of  the  volumes  of  the  cylinders 
so   that   the   total   work,   22,    done  by  the   engine  will   be 
almost  equally  divided  between  the  cylinders,  15,  but  such 
formulas  are  not  applicable  to  engines  having  much  com- 
pression   and    wire-drawing,    and    therefore    not    to     loco- 
motives.    Usually  for  engines  with  receivers,  these  formulas 
are   based  upon  a  constant  receiver  pressure.     A  rule  that 
has  been  frequently  used  is  that  the  ratio  of  the  volumes  of 
the  two  cylinders  should  equal  the  square  root  of  the  total 
number  of  expansions  desired.     This  rule  will  not  apply  to 
locomotives. 

48.  Ratio   of  Cylinders   as   Affected   by   Maximum 
Width  of  Locomotive. — So  far  as  economy  alone  is  con- 
cerned, the   maximum  over-all-width   of  a   locomotive  and 
the  necessity  for  a  minimum  weight  of   reciprocating  parts 
places  such  a  low  maximum   limit  upon  the  diameter  of  the 
1.  p.  cylinder  of  a  two-cylinder  receiver  compound  locomotive: 
that    it    cannot    always  be   given  a   volume  that  will  give 
the    best   theoretical  economy ;  however,  single   expansion 
locomotives    frequently    work'    with     such     low     efficiency 
that   a   compound    can    generally   be  given   sufficient  vol- 
ume in  the  1.  p.  cylinder  to  enable  it  to  show  a  substantial 
saving,  although  not  the  maximum  saving  that  would  be 
possible  under  other  and  more  favorable  conditions.     The 
loss  due  to  existing  types  of  valve  motion  is  so  great  that 
the  comparatively  minor  loss  incident  to  a  reasonable  limi- 
tation of  the  diameter  of  the  1.  p.  cylinder  practically  disap- 
pears in  comparison.     With  the  four-cylinder  compound,  it 
is  possible  to  get  a  more  economical  volume  of  1.  p.  cylin- 
der, but  it  would  appear  from  what  has  been  done  so  far 
that  the  four-cylinder  compound  introduces  further  troubles 
in  the  valve  motion,  and  the  saving  that  would  otherwise  be 
found,  by   reason   of  the   larger   1.  p.    cylinder,  is   to   some 


TOTAL    EXPANSION RATIOS    OF     CYLINDERS.          73 

extent  counterbalanced  by  a  decrease  in  the  efficiency  of 
the  valve  motion.  This  more  particularly  applies  to  high 
speed  locomotives. 

It  should  be  mentioned  here  that  the  use  of  a  double 
1.  p.  cylinder,  as  originally  proposed  by  Mallet,  112,  see 
Figs.  28  and  100,  will  give  a  sufficiently  large  1.  p.  cylinder 
capacity  to  any  compound  locomotive  of  the  two-cylinder 
type,  51. 

The  term  "  valve  motion,"  as  here  used,  refers  to  sizes 
of  ports  and  all  parts  of  the  steam  regulating  gear. 

49.  Ratios  of  Cylinders  Commonly  Used.  —  The 
cylinder  ratios,  which  have  been  used  for  two-cylinder  com- 
pounds, range  from  2.74  foi  small  engines  to  1.77  for  large 
engines.  Four-cylinder  engines  generally  have  a  ratio  of 
about  3.  Mr.  Mallet,  from  his  wide  experience,  has  said 
that  the  ratio  for  two-cylinder  engines  should  not  be  less 
than  2.  Mr.  von  Borries  recommends  ratios  of  2  for  freight 
locomotives  and  2.25  for  passenger  locomotives.  Ratios 
between  the  limits  of  2,  and  2.2  have  been  adopted  by  the 
majority  of  designers.  For  two-cylinder  compounds  in  the 
United  States  a  ratio  of  2.1  has  been  more  generally  used. 
The  foregoing  gives  prevailing  practice. 

As  has  been  shown,  mathematical  calculation  is  not  of 
much  value  in  determining  the  cylinder  ratios,  when  such 
calculation  is  based  upon  the  elementary  engine.  It  has 
also  been  shown  that  the  relative  mean  effective  pressures 
in  the  cylinders  is  more  dependent  upon  the  valve  arrange- 
ment at  the  present  time  than  upon  the  sizes  of  the  cylin- 
ders, and,  therefore,  as  the  power  in  the  cylinders  depends 
upon  the  mean  effective  pressure,  it  follows  that  the 
division  of  power  between  the  cylinders  depends  not  so 
much  on  the  sizes  of  the  cylinders  as  upon  the  action  of 
the  valve  motion  and  the  size  of  the  steam  passages.  And, 
further,  the  necessity  for  starting  trains  quickly  is  such  a 
controlling  condition  that  the  ratio  of  the  cylinder  volumes 


74  COMPOUND    LOCOMOTIVES. 

must  be  made,  not  what  is  most  efficient  from  an  economical 
stand-point,  but  rather  what  will  give  a  reasonably  uniform 
power  at  starting,  and  sufficient  power  on  the  h.  p.  side  to 
enable  the  engine  to  start  without  pulsations  and  jerks. 

It  is  evident  that  the  best  practical  ratio  of  cylinder 
volumes  must  have  been  originally  determined  by  experi- 
ment. Experiments  in  cylinder  ratios  have  been  made 
by  nearly  all  who  have  undertaken  to  introduce  two- 
cylinder  compounds,  and  many  have  traveled  over  the 
ground  of  investigation  covered  by  others,  with  the  hope  of 
getting  a  satisfactory  starting  power  and  an  even  power  dis- 
tribution with  better  theoretical  conditions  for  economy  In 
a  recent  case  of  this  kind,  the  locomotive  builder  had  to  take 
off  the  h.  p.  cylinder  and  replace  it  with  a  larger  one.  The 
ratio  at  first  was  about  3,  and  it  was  finally  made  about 
2.2  to  i. 

To  emphasize  and  explain  what  has  been  sa  d  regarding 
the  incidental  control  of  the  mean  effective  pressures  in  the 
h.  p.  and  1.  p.  cylinders  by  the  wire-drawing  and  compression, 
reference  is  now  made  again  to  Figs.  14  and  15,  Cards  I 
to  9.  See  also  Tables  C,  D,  E,  F,  G,  H,  and  I.  These  cards 
represent  about  the  best  that  has  been  done  in  the  way  of 
an  equal  distribution  of  power  between  the  h.  p.  and  1.  p. 
cylinders  of  large  two-cylinder  compound  locomotives. 

50.  Ratio  of  Cylinders  as  Affecting  Equalization  of 
Power  in  Two -Cylinder  Receiver  Compounds. — Theo- 
retical investigation  has  had  but  little  to  do  with  develop- 
ing the  proper  ratio,  but  practical  experiment  has  shown 
definitely  that  a  ratio  of  2.4  is  as  great  as  can  satisfactorily 
be  used  in  a  two-cylinder  compound,  and  that  a  ratio  of  2 
is  better,  as  it  makes  easier  the  approximately  equal  dis- 
tribution of  power  between  the  cylinders  at  different  speeds 
and  gives  better  results  in  starting  heavy  trains.  It  is  a 
simple  matter  to  adjust  the  equalization  of  the  power  in  the 
cylinders  of  a  two -cylinder  receiver  compound  with  a 


TOTAL    EXPANSION RATIO    OF    CYLINDERS.  75 

volume  ratio  of  2  when  the  valve  motion  is  good.  It  is 
easier  to  accomplish  this  equalization  with  a  ratio  of  2  than 
with  a  ratio  of  2.4.  With  a  ratio  of  2.4  it  is  practically 
impossible  to  equalize  the  power  between  the  cylinders  at 
high  speed,  unless  the  ports  and  passages  are  unusually 
large  and  the  valve  motion  most  excellent. 

All  things  considered,  it  is  better  to  assume  the  ratio  of 
volumes  of  cylinders  for  two-cylinder  receiver  compound 
locomotives  between  the  limit  of  2  and  2.2,  than  to  go  out- 
side of  these  limits  with  the  hope  of  obtaining  greater 
economy.  Within  these  limits,  it  does  not  matter  so  very 
much  what  the  ratio  is  ;  but,  as  has  been  said  before,  it  is 
easier  to  adjust  the  equalization  of  power  between  cylinders, 
particularly  for  high-speed  work,  when  the  lower  limit  is 
used,  and  in  addition  better  results  will  be  obtained  in 
starting  trains. 

Exact  equalization  of  power  is  not  necessary,  or  perhaps 
desirable.  A  variation  of  10  per  cent,  either  way  will  pro- 
*duce  no  harmful  results.  In  the  case  of  some  recent  two- 
cylinder  receiver  compounds,  the  greatest  variation  in 
power  from  starting  to  a  speed  of  67  miles  per  hour  is  5 
per  cent.  This  is  a  remarkably  close  equalization. 

51.  Ratio  of  Cylinders  and  Equalization  of  Power 
in  Non-Receiver  Compounds. —  For  four-cylinder  receiver 
or  non-receiver  compounds  having  duplicate  sets  of  cyl- 
inders on  the  two  sides,  where  the  equalization  of  power 
is  not  so  desirable  as  in  two-cylinder  receiver  compound 
locomotives,  a  ratio  of  from  2.7  to  3.2,  as  limits,  can  be 
chosen  without  error  and  without  materially  affecting  the 
economy  in  locomotive  work.  Probably  a  ratio  of  3,  for 
the  present  at  least,  will  be  found  perfectly  satisfactory. 

If  the  time  ever  comes  when  a  better  positive  acting 
valve  motion  is  devised,  8,  82,  and  one  that  will,  with  the 
assistance  of  larger  valves  and  steam  passages,  give  quicker 
and  greater  port  openings  and  will  postpone  the  point  of 


76  COMPOUND    LOCOMOTIVES. 

compression  nearer  to  the  end  of  the  stroke,  then  these 
remarks  about  the  cylinder  ratios  for  compound  locomotives 
will  perhaps  need  to  be  modified  ;  but  until  then  the  limits 
of  ratio  given  will  be  found  satisfactory. 

52.  Ratio  of  Cylinder  Volumes  to  the  Work  to  be 
Done.  —  The  ratio  of  the  cylinder  volumes,  not  to  each 
other  but  to  the  work  to  be  done,  is  an  important  matter. 
In  general,  in  this  country,  the  two-cylinder  receiver  com- 
pounds have  had  less  volume  than  they  should  have  for  the 
work  they  have  been  designed  to  do.  This  has  perhaps 
been  caused  by  the  timidity  with  which  designers  have 
undertaken  larger  cylinders  with  their  consequent  heavier 
reciprocating  parts  for  American  engines.  The  cylinder 
volumes  used  in  Europe  for  the  same  work  are  greater  in 
proportion  to  the  hauling  power  of  the  locomotive,  as 
determined  from  the  total  weight  on  drivers,  than  they 
are  here,  Table  L,  Appendix  Q.  On  the  other  hand,  the 
four-cylinder  non-receiver  engines  built  here  have  had  cyl- 
inder volumes  more  in  proportion  for  the  work  to  be  done,' 
and  more  in  accordance  with  European  practice.  This 
appears  from  Table  L,  which  gives  the  comparative'cylinder 
volumes  of  several  designs.  An  increase  of  total  cylinder 
volume  for  two-cylinder  compounds  above  that  now  gener- 
ally used  in  this  country  is  certainly  necessary  if  the  best 
attainable  efficiency  is  sought. 

For  the  Vauclain  compound  the  Baldwin  Locomotive 
Works  have  used  the  following  formula  for  a  number  of 
engines,  but  at  the  present  time  they  are  using  a  formula 
having  a  somewhajt  different  coefficient,  instead  of  2.7, 
and  this  gives  larger  cylinders  for  the  same  weight  of 
locomotive  : 


2-7PS. 
d2  =  -i-  d'2. 


TOTAL    EXPANSION RATIO    OF    CYLINDERS.  77 

In  these  formulas  the  following  are  the  meanings  of  the 
symbols  used : 

P  =  Pressure,  by  gauge,  at  admission  to  h.  p.  cylinder. 

S  =  Stroke  in  inches. 

D  =  Diameter  of  drivers  in  inches. 

W  =  Weight  on  drivers  in  pounds. 

d   =  Diameter  of  h.  p.  cylinder  in  inches. 

d'=  Diameter  of  1.  p.  cylinder  in  inches. 

Mr.  von  Borries  has  recently  said  that,  in  his  opinion,  at 
the  present  time  the  following  proportions  should  be  used : 

Cylinders. — Diameter  d  of  1.  p.  cylinder  to  be  calculated  by  the  formula 

d£-4T.D. 
p.  s. 

if  the  full  tractive  force  is  to  be  used  as  in  ordinary  goods  engines.     In  this  formula  is : 

T  =  Tractive  force  ^  -^fa  of  adhesive  weight. 

D  =  Diameter  of  driving  wheels. 

p  =  Boiler  pressure. 

s  =  Stroke  of  pistons. 

For  passenger  and  fast-traffic  engines,  where  calculation  is  difficult,  the  diameter 
of  1.  p.  cylinder  of  compound -engines  to  be  i^  the  diameter  of  cylinders  of  single 
expansion  engines,  raising  the  steam  pressure  at  least  15  pounds. 

Diameter  of  h.  p.  cylinder  to  be  0.7  of  1.  p. 

Receiver. — The  volume  must  not  be  smaller  than  h.  p.  cylinder,  better  1.50  of 
this. 

Ports. — The  dimensions  of  ports  are  shown  in  Table  M. 

TABLE   M. 


H.  p.  cylinder. 

L.  p.  cylinder. 

Clearance  (including  ports),  -  -  - 

0.05 

0.07  of  volume  of  1.  p.  cyl. 

Area  of  ports,  

Width  of  ports,  
Length  of  ports,  ------ 

0.04 

0.056 
0.56 

0.07  of  area  of  1.  p.  cyl. 

0.07  diameter  of  1.  p.  cyl. 
0.77 

For  freight  engines  dimensions  of  ports  can  be  5  per  cent,  smaller. 
Motion  and  Slide-Valves.— If  t,  is  the  width   of  1.  p.   steam-port  the  following 
proportions  should  be  used  : 

Travel  of  valves  for  middle  position  of  link,      -'       -        -        -        -        1.6  .t 
Outside  lap  of  both  valves,         -  0.7 1. 


COMPOUND    LOCOMOTIVES, 


Inside  clearance  of  h.  p.  valve,  - 0.20  t. 

Inside  clearance  of  1.  p.  valve,  --------  o. 

The  corresponding  sections  of  slide-valves  and  faces  are  shown  in  Fig.  27.     The 
dimensions  are  given  in  proportion  to  t  as  a  unit. 

The  link-hanging  rods  to  be  made  of  different  length,  so  that  0.4  cut-off  in  h.  p. 
cylinder  corresponds  to  0.5  in  1.  p.  cylinder. 

Greatest  cut-off  running  forward  to  be  0.77  in  h.  p.  and  0.8  in  1.  p.  cylinder. 


HiqHP.VALYE. 

5.7— H H 

—3.1 f  L3CH 

fcS^l  b^l 


LOWP.VALVH. 
6.6 


FIG.  27. 
von  Berries'  Proportions  of  Valve  Dimensions. 

Mr.  A.  Mallet  and  Mr.  A.  Brunner  have  found  from 
experience  that  a  ratio  of  2.25  is  preferred  to  any  other 
for  cylinders  of  two-cylinder  receiver  compounds. 


With 


FIG.  28. 
Lapage  Double  Cylinder. 

this  ratio  these  designers  have  used  the  same  cut-off  in 
both  cylinders.  With  a  ratio  of  2  a  longer  cut-off  is  needed 
in  the  1.  p.  cylinder. 

It  would  se'em  that  the  proposition  of  Mr.  Mallet,  and 
later  by  Mr.  R.  H.  Lapage,  to  use  a  double  1.  p.  cylinder, 
as  shown  by  Figs.  28,  29  and  100,  would  effectually  dispose 
of  the  problem  of  finding  room  for  a  large  1.  p.  cylinder. 


TOTAL    EXPANSION RATIO    OF    CYLINDERS.  79 

When  this  double  cylinder  is  used  in  conjunction  with  a 
crosshead  of  the  Vauclain  type,  shown  in  Fig.  119,  it  is  not 
clear  why  a  two-cylinder  receiver  compound,  if  such  it 
could  then  be  called,  having  in  reality  three  cylinders, 


FIG.  29. 
Lapage  Double  Cylinder. 

could  not  be  built  with  sufficient  cylinder  capacity  for  any 
of  the  largest  locomotives  now  made.  This  proposition  has 
considerable  merit,  and  if  two-cylinder  compounds  with 
receivers  are  continued  in  use,  and  there  is  much  prospect 
that  they  will  be,  it  is  probable  that  some  extended  practical 
use  will  be  made  of  this  suggestion. 


CHAPTER  VIII. 

RECEIVER  CAPACITY,  RE -HEATING  AND  SEQUENCE  OF 

CRANKS. 

53.  Receiver    Capacity. — The  capacity  of  a  receiver 
can  be  properly  based  on  the  capacity  of  the  h.  p.  cylinder. 
In   general,   the   greater  the   capacity   of  the   receiver  the 
more  readily  can  the  equalization  of  power  between  the  two 
cylinders  be  accomplished  by  an  adjustment  of  the  cut-off, 
22,  in   the  cylinders,  and  the   less  will  be  the   effect  of   a 
change   in   the   sequence   of   the   cranks.      Large    receiver 
capacities  give  less  variation  of  pressure  in  the  receiver,  and 
in   this  way  are   conducive  to  economy.     The  ratio  of  the 
receiver  volume  to  the  volume  of  the  h.  p.    cylinder    now 
commonly  used    for  locomotives     is    given    in    Table    Ui. 
Probably  in  no  case   is   it  advisable  to  use  a  receiver  with 
less  capacity  than  2.3  times  the  volume  of  the  h.  p.  cylinder, 
and   it  is   better  to   use   a  higher   ratio.     Some   successful 
four-cylinder  receiver  compounds  have  a  receiver  volume 
4*/z  times  the  volume  of  the  h.  p.  cylinder.     The  prevailing 
practice    here    is    shown    by  Table   Ui.      For    comfortable 
working  the  volume  of  the  receiver  should  not  be  less  than 
2.5  times  the  volume  of  the  h.  p.  cylinder. 

Mr.  A.  Brunner,  who  has  made  many  designs  of  com- 
pound locomotives  for  Mr.  Mallet,  is  of  the  opinion  that 
the  receiver  should  have  from  4  to  5  times  the  volume  of 
the  h.  p.  cylinder. 

54.  Re-Heating  and  Steam  Jackets. — The  receivers 
should   be  located   in  as  hot   a  place  as  possible  ;  not  so 
much   to   gain   re-evaporation  or  super-heat  as  to  prevent 
condensation.     If  the   receiver  is   exposed   to   the   atmos- 

80 


RECEIVER    CAPACITY RE-HEATING.  8  I 

phere,  the  condensation  in  cold  weather  would  be  so 
enormous  as  to  offset  any  possible  saving  from  compound- 
ing. There  is  no  doubt  but  that  some  re-evaporation  of 
the  moisture  in  the  steam  does  take  place  in  the  receiver  of 
a  compound  locomotive  when  the  receiver  is  in  the  smoke 
box,  more  particularly  when  the  engine  has  short  tubes  and 
is  working  hard,  as  on  a  grade,  or  whenever  the  conditions 
are  such  as  to  give  a  high  smoke  box  temperature  ;  but  there 
is  probably  no  material  saving  in  present  designs  of  com- 
pound locomotives  over  single  expansion  engines  that  results 
from  re-evaporation  in  the  receiver.  The  re-heating  must 
be  small  owing  to  the  short  time,  about  one-third  to  one- 
fifth  of  a  second,  that  the  steam  is  in  the  receiver  when  the 
engine  is  at  speed.  However,  all  that  is  gained  by  re- 
evaporation  is  purely  a  saving,  for  the  smoke  box  heat 
which  produces  the  re-evaporation  would  otherwise  be 
wasted  through  the  stack.  If  a  steam  jacket  is  used  on  the 
receiver,  or  on  either  of  the  cylinders,  the  steam  used  in  it 
for  re-heating  would  be  used  in  the  cylinders  if  there  were 
no  jackets,  and  therefore  the  saving  in  the  cylinders  from  a 
steam  jacket  is  offset  by  the  loss  of  the  steam  used  in  the 
jacket.  Mr.  F.  W.  Dean  has  tried  a  steam  jacket  on  a  two- 
cylinder  receiver  compound  locomotive  for  the  Old  Colony 
Road,  but  it  was  finally  abandoned  on  account  of  the 
difficulty  of  draining  it,  and  the  engine  now  runs  without 
the  steam  jacket.  The  space  in  the  jacket  now  serves  to 
give  better  heat  insulation  to  the  h.  p.  cylinder  on  which  the 
jacket  is  placed. 

As  it  does  not  matter  much  in  a  compound  engine 
whether  the  jacket  is  on  the  receiver  or  the  h.  p.  cylinder, 
it  is  probably  better,  if  a  steam  jacket  is  wanted,  to  put  the 
receiver  into  the  boiler  itself,  as  has  been  done  on  a  Lindner 
compound  in  Germany.  This  plan  removes  any  difficulty 
of  draining  the  jacket  and  gives  the  highest  possible  value 
to  steam  jacketing.  However,  as  has  been  said,  the  re- 


82  COMPOUND    LOCOMOTIVES. 

heating  in  the  receiver  brought  about  by  a  steam  jacket  is 
not  all  gain,  as, there  is  some  loss  of  steam  in  the  jacket  or 
in  the  boiler  as  the  case  may  be ;  but  with  re-heating  by  the 
smoke  box  gases,  all  re-heating  is  purely  gain.  It  is  prob- 
able that  such  gain  as  is  obtained  from  re-evaporation  in  a 
receiver  in  a  locomotive  smoke  box,  under  ordinary  con- 
ditions, is  greater  than  could  possibly  be  obtained  from  a 
steam  jacket  on  either  the  receiver  or  the  h.  p.  cylinder. 
It  is  now  generally  understood  that  a  steam  jacket  on  the 
1.  p.  cylinder  is  not  conducive  to  economy. 

In  order  to  gain  all  that  is  possible  by  a  re-evaporation 
in  the  receiver  produced  by  the  heat  in  the  smoke  box  gases, 
it  is  better  to  use  a  large  receiver  made  of  one  or  more 
copper  pipes.  It  seems  impractical  to  put  these  pipes  in 
the  hottest  part  of  the  smoke  box  ;  namely,  in  front  of  the 
tubes,  because  of  the  difficulty  in  reaching  the  tubes  for 
cleaning  and  repairing ;  hence,  it  is  customary  to  put  the 
receiver  pipe  around  the  top  of  the  smoke  box,  either  for- 
ward or  back  of  the  smoke-stack  opening. 

Cast  iron  receivers  have  been  used  generally  in  this 
country.  They  cost  less  and  have  greater  durability  than 
copper.  It  is  not  now  known  whether  the  thin  copper 
receiver  gives  a  compound  locomotive  greater  efficiency  than 
a  cast  iron  receiver. 

55.  Smoke  Box  Temperatures.  —  Smoke  box  tem- 
peratures vary  from  400  to  1,200  degrees,  according  to 
the  forcing  of  the  engine  and  the  length  of  the  tubes. 
Recently  there  has  been  a  decrease  in  smoke  box  tem- 
peratures with  new  designs  of  locomotives,  resulting  from 
the  use  of  larger  fireboxes  and  longer  tubes,  and  it  is 
probable  that  smoke  boxes  will  be  run  at  a  lower  temperature 
in  the  future  than  they  now  are,  but  in  no  case  will  they 
reach  so  low  a  temperature  as  to  remove  all  value  for  the 
purpose  of  re-evaporating  moisture  in  the  steam  in  the 
receiver  of  two-cylinder  receiver  compound  locomotives. 


RECEIVER    CAPACITY RE-HEATING.  83 

56.  Sequence  of  Cranks. — At  the  commencement  of 
the  use  of  compound  cylinders  for  locomotives  it  was 
questioned  whether  the  h.  p.  or  the  1.  p.  crank  should  pre- 
cede in  rotation,  but  as  soon  as  the  receiver  capacities  were 
made  sufficient,  it  was  found  that  there  was  little  or  no 
difference  which  crank  had  precedence  in  receiver  engines. 
For  non-receiver  engines  it  would  make  quite  a  difference 
which  crank  precedes  if  the  cranks  were  placed  at  an  angle 
with  each  other,  but  as  non -receiver  compounds  for  locomo- 
tives are  only  made  with  the  h.  p.  and  1.  p.  pistons  con- 
nected to  the  same  crank,  it  is  not  necessary  to  discuss  this 
special  case.  Practically,  the  sequence  of  cranks  need  not 
enter  as  a  problem  for  solution  in  compound  locomotive 
designing. 


CHAPTER    IX. 

MAXIMUM   STARTING    POWER   OF   LOCOMOTIVES. 

57.  Starting   with    Close    Coupled    Cars    and   with 
Free   Slack.  —  In   starting   a   train   it   makes    considerable 
difference  whether  the  train   is  close  coupled,  like  a  vesti- 
buled  passenger  train,  or  has  free  slack  as  with  a  link  and 
pin  coupling.     With  a  close  coupled  train  it  is  more  difficult, 
as  the  locomotive  can  only  move  forward  a  very  short  dis- 
tance before  the  entire  load  has  to  be  started,  whereas  with 
free  slack  the  locomotive  can  frequently  move  a  full  revo- 
lution before  taking  up  the  last  car.      For  this  reason  com- 
pound   locomotives    have    given    more  trouble    in  starting 
passenger  trains  than  freight  trains. 

58.  Starting  of  Two-Cylinder  Receiver  Compounds 
without    an    Independent   Exhaust   for   High-Pressure 
Cylinder. — Two-cylinder  compounds  can  generally  acceler- 
ate passenger  trains  without  difficulty,  but  there  are  certain 
positions  of  the  cranks  in  which  such  locomotives  have  a 
reduced  power,  and  when  in  such   position  the  two-cylinder 
compound  of  this  type  does  not  accelerate  trains,  either  pas- 
senger or  freight,  as  satisfactorily  as  the  ordinary  or  single 
expansion  engine.     The  reason  is,  that  while  the  maximum 
turning   moment   of   a  compound    locomotive    at    starting, 
which  occurs  when  the  1.  p.  crank  is  nearly  on  the  quarter, 
is  greater   than   the   starting   power  of   a   single   expansion 
engine   as  a  rule,  yet  the  minimum  starting  power,  which 
occurs  when  the  h.  p.  crank  is  about  on  a  quarter,  is  consid- 
erably  less   than   with  the  single   expansion  engine.     This 
result  comes  from  the  comparative  size  of  the  h  p.  cylinder, 
it  being  but  little  if  any  larger  than  one  cylinder  of  a  single 

84 


MAXIMUM    STARTING    POWER    OF    LOCOMOTIVES.       85 

expansion  locomotive,  and  yet  has  a  back  pressure  on  one 
side  of  the  piston  very  nearly  equal  to  one-half  the  boiler 
pressure,  whereas  the  single  expansion  cylinder  has  but  a 
very  small  back  pressure.  Hence,  while  the  compound  has, 
perhaps,  10  per  cent,  larger  cylinder,  it  has  fully  40  percent, 
less  effective  pressure.  This  is  probably  all  the  argument 
that  is  necessary  to  show  why  it  is  that  the  practical  con- 
ditions of  operation  compel  the  use  of  a  larger  cylinder  on 
the  h.  p.  side  of  the  two-cylinder  compound  than  is  generally 
used  for  a  single  expansion  engine.  See  Chapter  XVII  for 
argument  about  recent  tendency  in  starting  gears. 

59.  Starting  of  Two-Cylinder  Receiver  Compounds 
with  Independent  Exhaust  for  High-Pressure  Cylinder. 

-The  engines  of  this' class  start  and  accelerate  trains 
equally  as  well  as  single  expansion  locomotives,  and  are 
practically  such  at  low  speeds  when  the  separate  exhaust  is 
opened.  At  higher  speeds,  the  small  opening  allowed  for 
the  separate  exhaust  generally  causes  considerable  back 
pressure,  and  the  engine  will  not  work  well  with  single 
expansion  for  that  reason.  This  class  of  compounds  can 
generally  start  heavier  trains  than  single  expansion  loco- 
motives of  equal  rating,  for  the  reason  that  the  cylinders 
are  larger ;  but,  of  course,  the  limit  of  all  traction  engines 
lies  in  the  adhesion  of  the  drivers  to  the  rails  ;  hence,  the 
additional  cylinder  power  of  this  type  of  compound  is  of  no 
advantage  after  the  limit  of  adhesion  is  reached. 

60.  Starting  of  Four-Cylinder  Two-Crank  Receiver 
and  Non-Receiver  Compounds. — The  four-cylinder  two- 
crank  compounds   do   not  have  the   disadvantage   common 
with  two-cylinder  compounds  without  separate  exhaust  for 
the    h.  p.  cylinder,   at  starting,  as   live    steam   can    be   used 
in  both   1.  p.  cylinders,  one   on    each    side,  and  the  engine 
can    be     started     under    a  heavier    load    than  it    can    haul 
under  normal  conditions  of  compound  working.      Generally 
speaking,   four-cylinder   two-crank    compounds   have   more 


86  COMPOUND    LOCOMOTIVES. 

starting  power  and  more  ultimate  hauling  power  than  single 
expansion  locomotives  of  equal  rating.  This  applies  to  four- 
cylinder  tandem  receiver  compounds  and  all  four-cylinder 
compounds  having  but  two  cranks.  This  increase  of  hauling 
power  is  one  of  the  strong  claims  made  by  the  advocates  of 
four-cylinder  two-crank  compounds.  In  cases  where  it  is 
customary  for  single  expansion  engines  to  separate  trains  in 
two  parts  and  pull  each  part  separately  over  a  heavy  grade, 
joining  the  train  together  again  on  the  other  side,  generally 
called  "doubling  the  hill,"  the  four-cylinder  two-crank  com- 
pound and  the  two-cylinder  receiver  compound  having  inde- 
pendent exhaust  to  the  open  air  for  the  h.  p.  cylinder,  can  be 
made  to  haul  the  entire  train  over  the  hill  by  using  steam 
directly  from  the  boiler  into  the  1.  p.  cylinders  and  running 
the  train  at  a  comparatively  low  speed.  This  is  certainly  a 
decided  advantage  on  some  roads. 

61.  Starting    of    Four-Cylinder    Four-Crank    Com- 
pounds   with    Receivers.  —  The  starting  power    of    four- 
cylinder  four-crank  compounds  depends  upon  the  location 
of  the  cranks,  and  whether   parallel   rods   are   used.     With 
some  of  these    types  the    starting    power   has  been  small  ; 
with  others  it  has  been  ample,  128-134.     See  Appendix  K. 

62.  Starting  and  Hauling  Power  of  Single  Expan- 
sion Locomotives.  —  The  following  formula  has  been  much 
used  for  the  tractive  power  of  locomotives  : 


D 

in  which  d—  the  diameter  of  the  cylinders  in  inches,  p  —  the 
mean  effective  pressure  in  pounds  per  square  inch,  s  =  the 
stroke  in  inches,  D  —  the  diameter  of  the  driving  wheels  in 
inches,  and  T—  the  tractive  power  or  pull  at  the  rail  in 
pounds.  This  formula  is  based  upon  the  fact,  that,  neglect- 
ing friction,  the  work  done  in  both  cylinders  during  any 
period,  such  as  one  revolution,  is  equal  to  that  done  at  the 
circumference  of  the  driving  wheel  during  the  same  time.  It 


MAXIMUM    STARTING    POWER    OF    LOCOMOTIVES.       87 

is  convenient  and  practical,  as  it  gives  the  hauling  power 
of  the  locomotive  when  the  mean  effective  pressure  in  the 
cylinders  is  known.  The  tractive  power  by  this  formula 
includes  the  power  necessary  to  move  the  entire  mechanism 
of  the  locomotive  and  the  locomotive  itself.  It  is,  in  fact, 
the  entire  work  done  in  the  cylinders  reduced  to  an  equiva- 
lent pull  on  the  rail.  In  using  it,  a  deduction  must  always 
be  made  for  the  internal  friction  of  the  engine  and  for 
the  power  required  to  move  the  engine  and  tender  in  order 
that  the  actual  pull  on  the  train  itself  may  be  determined. 
Some  have  made  the  error  of  assuming  a  universal  value  for 
/,  namely,  85  per  cent,  of  the  boiler  pressure.  This  is 
greatly  in  error  when  applied  to  some  engines,  and  the  only 
safe  way  to  use  the  formula  for  a  given  engine  is  to  deter- 
mine, by  taking  indicator  cards  from  the  engine  in  question 
or  a  similar  one,  what  is  the  real  maximum  mean  effective 
pressure.  The  method  of  deducing  this  formula  will  be 
found  in  Appendix  H.  It  follows  from  the  method  of 
deduction  that  this  formula  gives  an  average  value  for  the 
pulling  power,  and  therefore  that,  while  it  furnishes  a  ready 
method  of  comparing  the  pulling  power  of  locomotives 
under  ordinary  conditions,  it  is  of  very  little  use  in  estimat- 
ing the  first  starting  power  from  a  stand-still,  since  the 
minimum  pull,  and  not  the  average,  is  the  practical  measure 
of  the  initial  starting  power  of  the  locomotive. 

In  the  single  expansion  locomotive,  assuming  that  steam 
can  be  admitted  during  the  full  stroke,  and  neglecting  the 
effect  of  angularity  of  connecting  rods,  the  minimum  pull 
occurs  when  one  crank  is  on  the  half  centre,  the  other  being 
.at  a  dead  point,  and  the  maximum  pull  is  developed  when 
both  cranks  make  an  angle  of  45  degrees  with  the  centre 
line  through  the  dead  points.  This  can  be  readily  demon- 
strated by  calculation,  or  by  a  graphical  construction. 

63.  Graphical  Representation  of  Hauling  Power.— 
There  are  several  methods  of  representing  rotative  efforts 


COMPOUND    LOCOMOTIVES. 


graphically,  one  of  which  is  shown  by  Fig.  30,  in  which  the 
dotted  line  a  .  .  a  represents  the  rotative  effort,  or  the  tan- 
gential pull  or  push,  on  one  crank  pin,  and  b  .  .  b  is  that  of 


FIG.  30. 

Diagram  Showing  Combined  Starting  Power  of  Both  Cylinders  of  a 
Single  Expansion  Locomotive. 

the  other  at   right   angles   to   it,  the   steam  pressure  being 
assumed  as  constant  throughout  the  stroke. 

The  method  of  construction  is  as  follows  :  Let  A  B  be 
the  length  of  the  circumference  of  a  circle,  of  which  CD, 
Fig.  31,  is  the  radius.  It  can  be  readily  shown  that  the 
component  D  F,  of  the  pressure  on  the  piston  D  H,  which 
tends  to  produce  rotation,  is  proportional  to  the  sine  of  the 
angle  a,  through  which  the  crank  has- 
turned  from  a  dead  point.  Divide  the 
line  A  B  and  the  circumference  in  Fig» 
31  into  the  same  number  of  equal  parts. 
Then  through  the  points  of  division  on 
A  B  lay  off  perpendicular  distances, 
such  as  k  d,  equal  to  the  lines  which 
represent  the  sines  of  the  angles  in 
Fig.  31,  such  as  K  D. 

The  dotted  curve  a  a  represents  the  variations  in  rotative 
efforts  on  the  crank  starting  from  C L  during  one  revolution, 
and  the  curve  b  b,  shown  by  a  broken  line,  represents  the 
variations  in  efforts  on  the  crank  starting  at  C  M,  or  at 
right  angles  with  the  first. 

The  total  rotative  effort  is  shown  by  the  ordinates  of 
the  full  line  curve  in  Fig.  3'o,  which  is  obtained  by  adding 


FIG.  31. 


MAXIMUM    STARTING    POWER    OF    LOCOMOTIVES.       8<> 

the  ordinates  of  the  curves  for  the  single  crank,  for  example, 
fm—fg-^fk.  It  is  evident  that  the  value  of  the  total 
efforts  varies  between  A  N  and  k  e.  In  the  first  case,  one 
crank  is  on  the  dead  point,  and  the  other  is  on  the  half  centre, 
or  midway  between  the  two  dead  points.  The  pull  at  the 
rail  is  then : 

\K  d2  x  /  X  s  -5-  A 

Which  is  .7854  of  the  tractive  power  as  found  by  the 
ordinary  formula.  In  the  second  case  the  pull  is  twice 
that  of  one  crank  when  making  an  angle  of  45  degrees 
with  the  centre  line,  or  it  is 

|-d2x/>x2x  .707^  ,  -^-  A 

Which  is  i.i  i  of  the  tractive  power  as  usually  estimated. 

It  is  also  clear  that  there  are  four  maximum  and  four 
minimum  points  during  a  revolution.  These  values  are 
determined  as  has  been  said,  on  the  basis  that  a  constant 
steam  pressure  can  be  maintained  throughout  the  stroke, 
which  would  be  the  case  in  starting  if  steam  could  be 
admitted  to  the  cylinder  during  the  whole  stroke.  But  when 
the  latest  cut-off  takes  place,  when  the  piston  is  some  dis- 
tance from  the  end  of  the  stroke,  as,  for  example,  at  21 
inches  with  24  inches  stroke,  the  engine  will  have  a  weaker 
position  for  starting  than  that  given  above  as  a  minimum. 
When  one  piston  is  21  inches  from  the  beginning  of  its 
stroke  the  other  will  be  about  4  inches  from  the  begin- 
ning of  its  stroke,  and  its  crank  will  have  turned  through 
about  50  degrees  from  a  dead  point.  If  cut-off  takes  place 
at  21  inches,  no  steam  can  be  admitted  to  that  cylinder 
during  the  remainder  of  the  stroke,  that  is,  if  the  start  occurs 
with  the  piston  in  this  position,  and  the  work  of  starting 
devolves  upon  the  other  cylinder. 

When  the  piston  has  moved  4  inches  from  the  begin- 
ning of  the  stroke  the  rotative  effort  is  about  ^  of  the 
maximum  for  one  cylinder,  and  is,  therefore,  about  .589 
of  the  tractive  power  as  usually  estimated.  This  cor- 


QO  COMPOUND    LOCOMOTIVES. 

responds  to  an  ordinate  of  the  curve  a  a,  •&  little  to  the 
right  of  k  d,  and  is  evidently  the  most  difficult  position 
from  which  to  start  the  single  expansion  locomotive.  The 
reduction  in  the  rotative  effort  on  account  of  the  fall  in 
pressure  due  to  the  expansion  after  cut-off  and  release  will  be 
slight.  This  can  be  shown  on  the  diagram  by  laying  off 
radial  distances  such  as  C  P  and  C  R  on  the  proper 
radii  to  represent  the  pressures  for  these  crank  positions, 
and  using  the  lines  P  Q  and  R  S  for  ordinates  in  Fig.  30, 
instead  of  those  used  before.  The  final  effect  is  shown  by 
the  dotted  curve  at  ??,  Fig.  30. 

As  the  locomotive  starts  the  mean  effective  pressure  in 
the  cylinders  will  be  somewhat  reduced,  but  the  reduction 
will  not  be  of  large  amount  within  what  may  be  called  the 
starting  limits,  or  until  the  link  would  ordinarily  be  hooked 
up.  As  the  speed  increases  the  inertia  of  the  reciprocating 
parts,  etc.,  will  be  sufficient  to  modify  the  form  of  the 
diagram  of  crank  efforts,  but  it  is  not  necessary  to  consider 
that  in  estimating  the  initial  starting  power. 

64.  Starting  Power  with  Mallet's  System  and  other 
Non- Automatic  Starting  Gears. — Turning  now  to  the 
compound  locomotive,  it  is  apparent  that  in  the  Mallet  and 
other  systems  having  independent  exhaust  for  the  h.  p. 
cylinder  the  starting  conditions  are  almost  identical  with 
those  in  the  single  expansion  locomotive.  If  the  h.  p. 
cylinder  is  of  the  same  size  as  one  cylinder  of  the  single 
expansion  locomotive,  and  the  cylinder  ratio  is  2,  it  is 
only  necessary  to  admit  steam  of  one -half  the  boiler 
pressure  to  the  1.  p.  cylinder  in  order  to  have  starting  power 
equivalent  to  that  of  the  single  expansion  engine,  the  same 
boiler  pressure  being  used.  If  the  1.  p.  initial  pressure  is 
greater  than  one-half  the  boiler  pressure,  the  starting  power 
of  the  compound  will  be  greater  than  that  of  the  single 
expansion  engine  in  all  positions  in  which  the  1.  p.  cylinder 
is  available  for  use  in  starting,  that  is,  except  when  the  1.  p. 


MAXIMUM    STARTING    POWER    OF    LOCOMOTIVES.       QI 

crank  is  on  a  dead  point,  or  when  the  1.  p.  valve  is  in  such 
a  position  that  steam  cannot  be  admitted.  If  the  boiler 
pressure  of  the  compound  is  higher  than  that  of  the  single 
expansion  engine,  and  the  h.  p.  cylinder  is  the  same  size  as 
one  of  those  of  the  single  expansion  engine,  the  starting 
power  of  the  compound  engine  of  this  type  will  be  the 
greater  in  about  the  proportion  of  the  two  boiler  pressures. 
65.  Starting  -Power  with  Worsdell,  von  Borries  and 
other  Automatic  Starting  Gears. — In  the  Worsdell  and 
von  Borries  type,  and  others  with  automatic  intercepting 
valves,  the  conditions  in  starting  are  quite  different  from 
those  just  described.  When  steam  is  admitted  to  the 


FIG.  32. 
Steam  Pressure  During  First  Revolution  with  an  Automatic  Starting  Gear. 

receiver  by  means  of  the  starting  valve,  the  intercepting 
valve  is  closed,  and  the  h.  p.  piston  therefore  starts  against 
the  pressure  of  the  steam  or  air  which  filled  the  receiver 
just  before  the  starting  valve  was  opened.  The  amount  of 
this  receiver  pressure  will  depend  upon  the  length  of  time 
during  which  the  engine  has  been  standing,  the  condition  of 
.  the  valves,  etc.  If  at  starting  the  h.  p.  crank  is  at  a  dead 
point,  the  pencil  of  an  indicator,  which  is  applied  to  the 
steam  end  of  the  h.  p.  cylinder  during  the  first  stroke,  will 
trace  a  line  similar  to  a  b  c,  Fig.  32.  The  back  pressure 
acting  against  the  other  side  of  the  piston  during  this  stroke 
is  shown  by  a  line  such  as  d  e,  the  pressure  at  e  being  some- 
what greater  than  that  at  d  on  account  of  the  compression 


Q2  COMPOUND    LOCOMOTIVES. 

in  the  h.  p.  cylinder  and  receiver.  The  initial  back  pressure 
is  assumed  in  the  present  case  as  equal  to  the  atmospheric 
pressure.  The  diagram,  a  b  c  e  d,  thus  represents  what  may 
be  called  the  effective  indicator  card  for  the  first  stroke  of 
the  h.  p.  piston. 

When  the  h.  p.  exhaust  opens  the  pressure  in  that  cyl- 
inder and  the  receiver  will  fall  to  some  point  g,  which  can 
be  only  approximately  determined  by  calculation.  It  is 
located  on  Fig.  32,  by  calculation  on  the  basis  of  no  con- 
densation or  evaporation  during  the  exhaust.  The  forward 
pressure  on  the  h.  p.  piston  during  the  second  stroke  will 
be  similar  to  that  during  the  first  stroke,  and  is  shown  in 
Fig.  32  by  h  k  I.  The  back  pressure  line  during  this  stroke 
will  consist  of,  first,  a  curve  g  m,  which  represents  the  com- 
pression by  the  h.  p.  piston  of  the  steam  which  fills  the 
space  between  the  h.  p.  piston  and  the  intercepting  valve, 
until  that  valve  opens  ;  and  second,  of  a  line  m  n,  of  nearly 
constant  pressure,  which  represents  the  back  pressure 
during  the  remainder  of  the  stroke,  after  the  intercepting 
valve  opens  and  the  starting  valve  is  closed. 

It  is  generally  assumed  that  the  pressure  of  the  steam, 
which  is  admitted  directly  to  the  receiver  in  starting,  is 
reduced  by  wire-drawing  to  about  one-half  the  boiler  pres- 
sure. Assuming  this  to  be  so,  the  h.  p.  cylinder  back 
pressure  will  become  sufficient  to  open  the  intercepting 
valve  when  about  5/g  of  the  second  stroke  has  been  accom- 
plished, as  indicated  at  m,  Fig.  32.  The  net  diagram  from 
which  the  effective  pressure  on  the  h.  p.  piston  for  the 
second  stroke  can  be  obtained  is  then  h  k  I  n  m  g. 

A  diagram  of  rotative  efforts  constructed  from  these 
indicator  cards  is  shown  in  Fig.  33  by  the  curve  A  E  C F B, 
from  which  the  reduced  effort  resulting  from  the  increasing 
back  pressure  during  the  second  stroke  is  apparent. 

The  distribution  of  work  in  the  1.  p.  cylinder  in  starting 
does  not  differ  from  that  in  the  single  expansion  engine. 


MAXIMUM    STARTING    POWER    OF    LOCOMOTIVES.       93 

The  rotative  effort  will,  therefore,  be  represented  by  a  curve 
such  as  H  K L  D  M,  Fig.  33,  which  has  the  same  form  as  the 
single  crank  curves  in  Fig.  30.  The  curve  in  Fig.  33  is 
constructed  on  the  basis  of  the  initial  1.  p.  pressure,  being 
one-half  of  the  boiler  pressure.  If  the  initial  pressure  is 
greater  than  this,  the  ordinates  of  the  curve  between 
H  and  K,  K  and  D,  etc.,  should  be  proportionately  in- 
creased. The  combined  effort  of  the  two  cylinders  is 
shown  in  Fig  33  by  the  full  line  curve.  The  intercepting 


P     Q     C 


J) 


FIG.  33. 

Starting  Power  During  First  Revolution  of  a  Compound,  with 
Automatic  Starting  Gear. 

valve  opens  at  about  the  point  f,  and  from  that  point  the 
engine  will  work  as  a  compound. 

It  has  been  already  shown  that  when  so  working  with 
the  customary  pressures  the  power  developed  at  late  cut- 
offs is  less  than  that  of  the  single  expansion  engine.  The 
location  of  the  point  at  which  the  intercepting  valve  opens 
depends  upon  the  pressure  in  the  receiver  before  starting,  the 
pressure  of  the  steam  admitted  to  the  receiver  by  means  of 
the  starting  valve,  and  the  size  and  location  of  the  receiver. 
For  any  given  combination  of  conditions  it  will  be  found 
.at  a  definite  distance  from  the  point  C,  or  from  the  end  of 
the  first  stroke  of  the  h.  p.  piston.  In  the  present  case  this 
point  was  found  to  be  about  $/%  of  the  stroke  from  C. 

It  is  obvious  that  this  action  is  not  at  all  dependent  upon 
t  e  first  stroke  of  the  h.  p.  piston,  but  only  upon  the  exhaust 
from  that  cylinder.  It  follows  from  these  considerations 
that,  if  the  h.  p.  crank  is  at  a  dead  point  at  starting,  the 
^engine  will  move  through  something  over  ^  of  a 


94  COMPOUND    LOCOMOTIVES. 

revolution  before  compound  working  begins  :  but,  on  the 
other  hand,  if  the  h.  p.  piston  is  at  the  position  correspond- 
ing to  P,  or  near  the  point  at  which  cut-off  takes  place,  the 
compound  working  will  begin  after  about  T76  of  a  revolu- 
tion. If  the  h.  p.  crank  is  in  some  position  such  as  Q,  at 
which  the  steam  valve  is  closed,  the  starting  must  be 
accomplished  by  the  1.  p.  cylinder  alone ;  but  after  a 
slight  movement,  sufficient  to  carry  the  h.  p.  crank  over  the 
dead  point,  the  cycle  will  continue  as  if  started  at  A,  the 
effect  being  to  prolong  the  time  of  direct  working  of  the 
1.  p.  cylinder  to  about  ^  of  a  revolution. 

After  compound  working  commences,  and  while  admit- 
ting steam  for  as  much  of  the  stroke  as  possible,  the  combined 
diagram  of  rotative  efforts  would  be  similar  to  Fig.  30,  but 
with  a  smaller  mean  effective  pressure,  the  proportion  being, 
with  boiler  pressures  of  170  and  I  50  pounds  in  the  two  types, 
not  greater  than  1 10  to  122,  as  has  been  already  mentioned. 
The  two  diagrams,  Figs.  30  and  33,  are  not  drawn  to  the 
same  scale  of  pressures,  but  the  shape  of  the  full  line  curves 
represents  with  reasonable  accuracy  the  variations  in  starting 
power  in  the  single  expansion  and  compound  locomotives. 
In  conclusion,  it  appears  that,  with  the  pressure  customary 
in  the  two  forms,  the  pulling  power  of  the  Worsdell  and  von 
Borries  type,  and  others  with  automatic  intercepting  valves, 
in  starting  may  be  greater  than  that  of  the  single  expan- 
sion engine  having  cylinders  of  the  same  size  as  the  h.  p. 
cylinder,  during  the  first  half  revolution  approximately, 
but  that  after  this  the  power  of  the  compound  engine 
diminishes  until  it  is  from  So  to  85  per  cent,  of  that  of  the 
single  expansion  engine. 

66.  Starting  Power  with  the  Lindner  System.— The 
maximum  starting  power  of  the  two-cylinder  Lindner  type 
with  latest  type  of  Lindner  starting  gear,  and  without  inter- 
cepting valve,  is  about  the  same  as  the  maximum  with  the 
two-cylinder  type  having  automatic  intercepting  valves,  but 


MAXIMUM    STARTING    POWER   OF    LOCOMOTIVES.       95 

is  much  less  than  the  two-cylinder  type  having  independent 
exhaust  for  the  h.  p.  cylinder.  Appendix  L  gives  analysis 
of  the  starting  power  of  a  Lindner  engine. 

67.  Starting  Power  of  Three-Cylinder  Three-Crank 
Compounds.  —  The  starting  power  of  three-cylinder  com- 
pounds, when  the  drivers  are  coupled  together  with  parallel 
rods,  is  about  the  same  as  with  the  two-cylinder  type.     If 
the  drivers  are  not  coupled,  as  with  the  Webb  type,  the  ulti- 
mate starting  power  is  dependent  upon  the  accidental  loca- 
tion of  the   crank  at  the  time   of  starting.     The  minimum 
starting  power  for  full   cut-off  and  full  throttle  of  a  three- 
cylinder  type  without   parallel  rods  is  lower  than  the  mini- 
mum of  the  two-cylinder  receiver  type.     See  Appendix  I. 

68.  Variation  of  Hauling  Power  with  Four-Cylinder 
Two-Crank  Receiver  and  Non-Receiver  Compounds.  — 
The  curve  of  variation  of  hauling  power  during  a  complete 
revolution  in  a  two-crank  four-cylinder  non-receiver  com- 
pound  or  four-cylinder   tandem    receiver    compound,  does 
not  differ  materially  from  that  of  a  single  expansion  engine, 
as  both  sides  are  identical  in  action.     However,  with  the  same 
number  of  expansions  in  the  four-cylinder   and  the   single- 
expansion  engine,  the  hauling  power  is  more  uniform  in  the 
compound,  more  particularly  for  the  reason  that  the  cut-off 
in  both  cylinders  in  the  compound  is  later  than  in  the  single 
expansion  engine.      In  any  engine,  the  later  the  cut-off   the 
more  uniform  will  be  the  hauling  power  during  a  complete 
revolution  at    slow   speed.      At   high   speeds   this   is   much 
modified    by   the    inertia    of    the    reciprocating    parts,    see 
Appendix  P.      Uniformity  of  pull  on  a  train  is  of  more  im- 
portance  in  starting  and  at  slow  speed  than  at  high  speed, 
as  at  slow  speed  a  variation-in  the  pulling  power  may  be  felt 
by  the  passengers  in  a  train. 

The  foregoing  statements  about  four-cylinder  compounds 
apply  more  particularly  to  the  non-receiver  Vauclain,  John- 
stone,  and  tandem  types,  and  to  the  tandem  form  generally, 


<)6  COMPOUND    LOCOMOTIVES. 

but  are  also  true  of  four-cylinder  receiver  compounds  with 
four  cranks  in  which  the  cranks  are  almost  evenly  divided 
in  position  on  a  circle  and  with  parallel  rods  between  the 
axles  having  cranks. 


CHAPTER    X. 

CONDENSATION    IN    CYLINDERS. 

69.  Range  of  Temperature. — When  compound  engines 
are   well    designed   and   are  working  under   favorable  con- 
ditions, the  loss  from  condensation  of  steam  in  trie  cylinders 
should  be  less  than  with  single  expansion.     This  arises  from 
the  lower  range  of  temperature  in  the  cylinders ;  the  range 
of  pressure  being  less  in  the  cylinders  of  the  compound,  it 
follows   that   the   range  of  temperature  would  also  be  less. 
However,  the  gain  in  efficiency  by  saving  in  condensation 
may   be  more  than   offset  by  results  of  faulty  mechanical 
arrangement.    If  the  cylinders,  steam  passages,  and  receiver, 
are  not  well  protected  from  radiation,  the  loss  by  condensa- 
tion from  this  cause  may  more  than  offset  the  saving  from 
the   reduction    of  condensation  brought  about  by  a  lower 
range  of  temperature  in  the  compound  cylinders. 

70.  Need  of  Covering  Hot  Surfaces  to  Prevent  Ra- 
diation.— It  is  a  very  bad,  but  common  practice,  in  locomo- 
tive  construction,   and  one  that  has   descended    from  the 
past,  to  construct  cylinders  for  locomotives  with  the  walls 
of  the  steam  passages  exposed  directly  to  the  atmosphere 
without  covering  on  the  outside.     Steam  chests  and  cylinder 
heads  are  likewise  very  poorly  insulated  in  common  practice. 
The  loss   from   these  defects  alone    is  so   great  that  it  is 
hardly  worth  while  to  go  to  the  trouble  to  use  compound 
cylinders   unless    the    heat    insulation    is    improved.     This 
common   defect   in  locomotive   construction  has  been  the 
subject  of  severe  criticism  by  mechanical  engineers  who  are 
familiar  with  the  better   class  of  designing  for   marine  and 
stationary  engines.     Just  now  some  railroad  companies  have 

97 


g8  COMPOUND    LOCOMOTIVES. 

taken  the  matter  in  hand  and  are  using  somewhat  better 
heat  insulation  for  all  parts  that  are  exposed.  Locomotive 
builders,  however,  have  not  yet  considered  it  worth  while 
to  reduce  radiation  by  better  insulation,  probably  because 
of  the  lack  of  appreciation  of  these  losses  on  the  part  of 
those  who  purchase  locomotives.  Mr.  F.  W.  Dean,  54,  in 
designing  some  engines  for  the  Old  Colony  Railroad,  has 
separated  the  steam  pipes  from  the  walls  of  the  cylinders, 
and  has  used  a  better  degree  of  heat  insulation  than  is 
common.  From  the  results  obtained  from  his  engine,  it 
would  appear  that  the  better  insulation  has  been  of  a 
decided  advantage.  The  condensation  of  steam  in  a  loco- 
motive is  one  of  the  sources  of  loss,  and  the  highest 
possible  saving  of  the  compound  cannot  be  obtained  with- 
out a  proper  insulation  of  all  pipes,  passages,  and  recepta- 
cles for  steam. 

71.  Condensation,  Leakage  of  Valves  and  Re-Evap- 
oration as  Determined  from  Indicator  Cards. — In  the 
discussion  of  a  method  of  analysis  of  combined  indicator 
cards,  the  losses  due  to  condensation  are  considered,  42,  44. 
In  addition  to  that  discussion,  the  following  further  analysis 
of  Fig.  26,  and  some  cards  from  other  types  of  engines,  will 
be  found  instructive.  This  analysis  shows  how  the  steam 
weights  calculated  from  actual  indicator  cards  vary  at  dif- 
ferent points  during  a  stroke  in  the  h.  p.  and  1.  p.  cylinders 
of  two-cylinder  receiver  and  four-cylinder  non-receiver 
compounds.  These  results  are  given  in  Tables  N,  J  and 
O.  Table  N  gives  the  fundamental  data  regarding  the 
engines  that  is  used  to  make  the  calculations  from  the 
indicator  cards.  Table  J  gives  the  final  results  of  the 
calculation,  and  shows  the  weight  of  steam  used  per  stroke 
in  both  cylinders,  and  the  per  cent,  of  increase  or  de- 
crease of  weight  of  steam  used  in  the  1.  p.  cylinder  above 
or  below  that  used  in  the  h.  p.  cylinder,  this  data  being 
taken  from  the  measurements  on  the  indicator  cards.  The 


CONDENSATION    IN    CYLINDERS. 


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2  2  s 


CONDENSATION    IN    CYLINDERS  IOI 

weight  of  steam  shown  to  be  in  the  cylinder  at  the  ter- 
mination of  the  compression,  period  is  subtracted  from  the 
weight  of  steam  in  the  cylinders  near  the  end  of  the 
expansion  period.  The  remainder  is  taken  as  representing 
the  amount  of  steam  used  in  the  cylinders,  as  shown  by  the 
indicator  cards,  30-31,  42. 

Table  O  shows  the  distribution  of  the  steam  at  different 
parts  of  the  stroke  for  an  indicator  card  from  the  Vauclain 
engine.  See  Fig.  26. 

TABLE    O. 

Giving  Calculated   Weight  of  Steam  at  Different  Points  of  an    Indicator  Card 
from  Vauclain  Compound  No.  82  in  C.  B.  &>  Q.  Tests. 

Weight  of  steam  at  point  3,  the  terminal  of    expansion  in 

h.  p.  cylinder. 5913  Ibs  » 

Weight  of  steam  in  valve  at  H,  the  cut-off  in  1.  p.  cylinder     .0434  " 

Weight  of  steam  in  1.  p.  clearance  space    at    L 0832  " 

Ratio  of  weight  of  steam  in  valve  at  H  to  the  weight  of 

steam  discharged  by  the  h.  p.  cylinder  at  point  3 ....          7.3$ 

Ratio  of  weight  of  steam  in  1.  p.  clearance  space  at  L  to 
the  weight  of  steam  discharged  by  the  h.  p.  cylinder 
at  point  3 14.1$  • 

Total  addition  to  weight  of  steam  discharged  from  h.  p. 
cylinder  at  point  3  resulting  from  the  admixture  with 
the  steam  in  valve  and  that  in  1.  p.  clearance  space. 
Based  on  the  measurement  of  the  weight  in  valve  at 
H  and  in  the  1.  p.  clearance  at  L,  no  allowance  being 
made  for  condensation 21.4$ 

Actual  addition  to  weight  of  steam  discharged  from  h.  p. 
cylinder  at  point  3,  based  on  measurement  of  indica- 
tor card  at  K 12.0$ 

Difference  between  the  actual  addition  of  steam  weight 
measured  at  K  and  the  addition  that  would  be  found 
if  the  steam  at  H  in  valve,  and  the  steam  at  L  in  1. 
p.  clearance  space,  had  been  retained  without  con- 
densation or  leakage  and  had  been  added  to  that 

incoming  from  the  h.  p.  cylinder,  21.4—12= 9.4$ 

It  has  been  claimed  that  the  steam  pressure  in  the  valve  when  the  h.  p. 

cylinder  exhausts  at  point  3  is  the  same  as  the  pressure  of  that  exhaust,  but 

in  this  case  the  valve  pressure  can  be  but  49  pounds  absolute,  or   the    same  as 

that  at  H,  while  the  pressure  of  the  exhaust  from  the  h.  p.  cylinder  is  that  at 

point  3  or  126  pounds  absolute. 

The  weight  of  the  steam  in  the  valve  with  49  pounds  pressure,  absolute,  is  but 

.0434  pounds,  while  the  weight  with  126  pounds  pressure  would  be  .1205  pounds. 


IO2  COMPOUND    LOCOMOTIVES. 

72.  Examples  of  Determination  of  Condensation, 
Leakage,  and  Re-Evaporation,  from  Various  Indicator 
Cards. — Table  J  gives  some  data  about  steam  use  in  com- 
pound locomotives.  The  columns  of  particular  interest  are 
those  which  show  the  per  cent,  of  increase  or  decrease 
of  the  steam  used  in  the  1.  p.  cylinder.  It  will  be  noticed 
that  the  cards  taken  from  the  two-cylinder  compounds  show 
less  steam  in  the  1.  p.  cylinder  than  in  the  h.  p.  This  would 
point  to  a  condensation  somewhere,  but  it  is  not  possible  to 
say  where  it  takes  place  without  further  analysis.  It  may 
be  in  the  receiver,  as  in  any  compound  engine  with  a 
receiver,  if  the  receiver  is  not  provided  with  an  efficient 
re-heater,  there  is  some  loss  of  steam  weight.  This  is  very 
well  shown  in  some  tests  of  a  triple  expansion  engine  made 
by  Professor  Peabody,  of  the  Massachusetts  Institute.  From 
the  results  of  the  analysis  of  the  cards  from  the  C.,  B.  &  Q. 
compound  it  will  be  noticed  that  the  crack  in  the  cylinder 
saddle  caused  so  much  leakage  as  to  show  a  considerable 
increase  of  steam  used  in  the  1.  p.  cylinder.  In  closing 
upon  this  very  important  matter  of  the  relative  amounts  of 
steam  shown  in  the  h.  p.  and  1.  p.  cylinders,  it  is  necessary 
to  add  that  a  10  per  cent,  difference  in  the  steam  used  by 
the  two  cylinders  is  not  necessarily  followed  by  a  10  per 
cent,  loss  of  efficiency  in  the  engine,  and  it  may  be  that  no 
material  loss  follows  as  much  difference  as  this,  for  much 
depends  upon  the  grade  of  expansion  and  conditions,  42,  44. 

The  object  of  making  such  analyses  as  this  is,  to  learn 
about  the  rate  of  re-evaporation  in  compound  locomotive 
cylinders.  Re-evaporation  must  not  be  confused  with  leak- 
age. With  steam  containing  moisture  when  the  volume 
increases  the  apparent  weight  of  steam  increases  also.  This 
arises  from  the  fact  that  as  the  steam  expands  there  is  more 
heat  in  it  than  is  necessary  to  keep  the  steam  at  the 
temperature  corresponding  to  the  reduced  pressure,  and 
also  some  heat  is  given  back  from  the  cylinder  walls,  which 


CONDENSATION    IN    CYLINDERS.  IO3 

have  been  previously  heated,  and  this  extra  heat  goes  to 
evaporate  some  of  the  moisture  that  is  contained  in  the 
steam.  This  moisture  results  from  the  condensation  while 
the  steam  is  entering  the  cylinder  from  the  boiler  up  to 
cut-off.  The  amount  of  steam  condensed  varies  materially 
with  different  engines,  but  a  rough  approximation  shows 
that  the  Baldwin  engine  on  this  test  condensed  something 
over  30  per  cent,  of  the  entering  steam  while  the  cylinders 
were  being  filled  from  B  to  E,  Fig.  26.  The  condensation 
in  some  types  of  engine  runs  as  high  as  60  per  cent.,  and  in 
other  engines,  under  particularly  favorable  conditions,  as  low 
as  20  per  cent.,  and  perhaps  even  lower  in  the  first  cylinder 
of  the  best  designed  triple  expansion  engines  with  steam 
jackets.  Just  as  the  steam  condensed  during  admission 
evaporates  during  expansion,  on  account  of  the  excess  of 
heat  over  and  above  that  necessary  to  keep  the  steam  at  a 
temperature  corresponding  to  the  pressure,  and  further  by 
the  heat  received  from  the  cylinder  walls,  so  during  com- 
pression some  of  the  steam  condenses  by  reason  of  the  heat 
taken  from  it  to  heat  up  the  cylinder  head,  the  piston  head, 
and  the  walls  of  the  steam  passage.  These  analyses  of  loss 
of  heat,  and  the  corresponding  loss  in  steam  weight,  are 
interesting  mainly  in  showing  that  the  actual  steam  lines 
do  not  correspond  with  the  usual  theoretical  steam  line 
drawn  for  the  sake  of  comparison  on  combined  indicator 
cards,  43. 

The  hyperbola  which  is  frequently  drawn  to  show 
whether  the  engine  leaks  or  not,  does  not  take  into  account 
the  full  change  in  temperature  during  expansion,  41,  43.  The 
adiabatic  curve  is  an  approximate  curve  which  approaches 
very  closely  to  the  theoretical  expansion  of  steam  while 
doing  work  when  there  is  no  loss  or  gain  of  heat  due  to 
the  heating  of  cylinder  walls,  etc.  It  takes  account  of  the 
heat  taken  from  the  steam  to  do  work.  Owing  to  the  re- 
evaporation  in  steam  cylinders,  it  is  generally  the  case  that 


V*"  0»  TH**NP 

wiraasjTr] 


104  COMPOUND    LOCOMOTIVES. 

the  hyperbola  corresponds  more  nearly  to  the  actual 
expansion  line  on  an  indicator  card  than  does  the  adiabatic. 
In  compression  the  actual  compression  line  differs  widely 
from  both  the  hyperbola  and  the  adiabatic,  6. 

The  weights  of  the  steam  present  in  the  cylinders  have 
been  calculated  for  several  points  during  the  expansion  of 
the  steam  in  the  two  cylinders,  Fig.  26,  and  are  as  follows  : 

The  weight  at  point  I  is  .57  pounds;  at  the  point  2  it 
is  .58  pounds;  at  the  point  3  it  is  .59  pounds.  Thus  is 
shown  the  continual  re-evaporation  and  corresponding 
increase  in  apparent  steam  weight  during  expansion  in  the 
h.  p.  cylinder. 

The  subject  of  cylinder  condensation  is  a  very  complex 
one  and  cannot  be  treated  here  from  a  theoretical  stand- 
point, as  theoretical  studies  of  the  subject  are  of  little  value 
unless  the  constants  of  heat  absorption  are  known.  These 
have  never  been  determined  for  locomotives.  The  most 
practical  instruction  is  :  insulate  all  exposed  hot  surfaces  of 
the  boiler  and  live  steam  passages  and  receptacles  as  fully 
as  the  best  insulation  will  allow,  and  do  this  regardless  of 
cost  where  fuel  is  high  in  price,  70. 


CHAPTER  XI. 

THE  VALVE  GEAR  ADJUSTMENTS. 

It  has  been  shown  that  when  the  valve  motion  is  good 
and  the  receiver  is  of  large  volume,  the  division  of  the 
total  work  between  h.  p.  and  1.  p.  cylinders  can  be  equalized 
with  sufficient  approximation  for  practical  work  by  ad- 
justing the  cut-off  in  the  cylinders.  This  is  readily  ac- 
complished for  locomotives  that  run  always  in  the  same 
direction  by  adjusting  some  part  of  the  valve  gear  without 
increasing  the  complication.  This  is  true  of  the  Stephen- 
son,  Allen,  Joy,  Walscheart,  and  other  positive  motions. 
It  is  generally  accomplished  by  changing  the  position  of 
one  of  the  links  with  respect  to  the  other,  either  by  short- 
ening or  lengthening  the  link  hanger,  or  by  off-setting  one 
of  the  arms  of  the  reverse  shaft.  Several  modifications  of 
the  link  motion  that  have  been  adopted  to  change  the 
relative  cut-off  in  the  cylinders  will  be  given  in  what 
follows. 

For  locomotives  that  run  in  both  directions  the  adjust- 
ment of  the  cut-off  is  more  difficult,  and  the  devices  for 
doing  this  introduce  some  new  details  of  construction  and 
are  in  some  cases  complicated.  The  simplest  way  in  which 
to  get  a  difference  in  cut-off  in  the  cylinders,  in  both  for- 
ward and  back  motion,  for  locomotives  that  run  in  both 
directions,  is  to  give  a  different  valve  travel  or  outside  lap' 
to  the  different  cylinders.  In  all  cases  not  enough  differ- 
ence can  be  produced  in  this  way  to  accomplish  the  desired 
result  without  making  the  steam  distribution  in  one 
cylinder  much  less  efficient  than  in  the  other,  but  where 
the  cylinder  ratio  is  selected  within  the  proper  limits,  and 

105 


106  COMPOUND    LOCOMOTIVES. 

the  receiver  has  sufficient  capacity,  and  the  valve  travel 
and  steam  ports  are  ample,  the  adjustment  can  be  made 
with  perfect  satisfaction  by  changing  the  travel  or  outside 
lap  to  adjust  the  cut-off,  45-56,  77-81.  In  Tables  P,  Q,  R, 
S,  T,  U,  Ui  and  V,  will  be  found  the  result  of  some  changes 
of  this  kind  and  the  opinions  of  various  designers  on  this 
matter.  With  the  Joy  gear,  the  variation  in  cut-off  may  be 
produced  by  inclining  the  sliding  links  to  each  other. 

73.  Mallet's  System  of  Cut-Off  Adjustment. — In  the 
earlier  Mallet  engines  the  lifting  shaft  is  divided  so  that 
th$  valve  motion  of  each  cylinder  is  to  a  certain  extent 


FIG.  34. 
Mallet  Regulating  Device. 

independent  of  the  other.  The  h.  p.  valve  gear  is  con- 
trolled by  a  screw  and  nut,  which  takes  the  place  of  the 
ordinary  quadrant.  The  nut  which  is  on  the  h.  p.  reverse 
lever  carries  a  short  sector  or  quadrant,  and  a  latch  on  the 
1.  p.  reverse  lever  works  in  this  sector.  '  The  effect  is  that 
both  cylinders  can  be  reversed  by  moving  the  h.  p.  lever  ; 
while  by  adjusting  the  1.  p.  lever  the  cut-off  in  that  cylinder 
may  be  made  either  later  or  earlier  than  in  the  h.  p.  cylinder. 
Mr.  Mallet  has  adopted  a  differential  motion  for  the 
purpose  of  obtaining  a  later  cut-off  in  the  1.  p.  cylinder  in 
both  forward  and  backward  gear.  The  principle  of  this 
motion  is  illustrated  by  Fig.  34.  In  this  Fig.,  A  is  the 


VALVE    GEAR    ADJUSTMENTS, 


107 


lifting  shaft  and  B  is  an  auxiliary  shaft.  The  lifting  arm 
M  of  the  h.  p.  link  and  the  arm  C  are  keyed  to  the  lifting 
shaft,  while  the  1.  p.  lifting  arm  N  and  the  arm  H  are  in 
one  piece,  which  turns  about  this  shaft.  The  slotted  arm 
D  and  the  arm  E  are  keyed  to  the  auxiliary  shaft.  The 
arm  C  carries  a  block  which  slides  in  the  slotted  piece  D. 
The  parts  are  shown  in  Fig.  34  in  a  position  for  backing, 
the  1.  p.  link  being  raised  higher  than  the  h.  p.  link  and 
therefore  cutting  off  later.  In  full  backing  gear  the  arms 
M  and  N  would  be  parallel  and  hence  give  the  same  cut- 
off in  both  cylinders.  In  mid-gear  the  arms  C  and  D  are 
on  the  center  line  A  B,  while  in  forward  gear  or  to  the  left, 
the  lifting  arm  N  is  lowered  more  rapidly  than  the  arm  M. 
Mr.  Mallet  gives  the  following  as  the  distribution  obtained 
with  this  arrangement : 

Forward  Gear. 

High-pressure  cylinder 70     .60 

Low-pressure  cylinder 70     .65 


•50 
.60 


.40 
•55 


•30 
•50 


j  Backward  Gear. 
.0         .0     .60     .70 
.0  |      .0     .65     .70 


FIG.  35. 
C.  B.  &  Q.  Link  Hunger  Adjustment. 


io8 


COMPOUND    LOCOMOTIVES, 


FIG.  36. 
Chicago,  Burlington  &  Quincy  Gear. 

74.  Chicago,  Burlington  &  Quincy  System.  —  Mr. 
William  Forsyth,  Mechanical  Engineer  of  the  Chicago,  Bur- 
lington &  Quincy  Railroad,  has  designed  a  variable  cut-off 
gear  for  the  two  cylinders  of  a  Lindner  compound  by  making 
one  of  the  reverse  shaft  arms  loose  on  the  shaft.  The  loose 
arm  is  a  bell  crank  with  a  vertical  arm  similar  to  the  one  used 
for  reverse  shafts  on  American  engines.  From  the  top  of 
the  loose  arm  a  short  reach  rod  runs  back  about  four  feet, 
and  is  there  attached  to  the  main  reach  rod  running  to  the 
reverse  lever.  With  this  arrangement,  by  making  one  of  the 
vertical  arms  shorter  than  the  other,  a  movement  of  the 
reverse  lever  causes  a  different  angle  of  rotation  of  the  two 


VALVE    GEAR    ADJUSTMENTS, 


IOQ 


reverse  shaft  arms,  and  one  link  can  be  dropped  lower  than 
the  other  while  running  in  either  direction.  This  arrange- 
ment worked  satisfactorily  and  the  distribution  was  excel- 
lent. It  was  found,  however,  that  the  lengthening  of  the 
1.  p.  link  hanger  accomplished  the  same  end,  for  regular 
freight  engines,  and  the  second  compound  was  built  with  the 
hangers  at  different  length,  as  given  in  Figs.  35  and  36. 

75.  Heintzelrhan  System.  —  On  the  Southern  Pacific 
the  following  plan  for  adjusting  the  cut-off  has  been  devised 
by  Mr.  T.  W.  Heintzelman.  See  Figs.  37  and  38. 


FIG.  37- 
Heintzelman   Gear. 

The  horizontal  arm  of  the  reverse  shaft  has  a  slot  in 
which  slides  a  block.  To  this  block  is  attached  the  upper 
end  of  the  link  hanger,  and  also  one  end  of  a  horizontal 
link.  The  horizontal  link  at  the  other  end  is  attached  to  a 
bracket  on  the  guide  yoke  or  any  other  convenient  part  of 
the  locomotive.  This  device  is  put  on  the  h.  p.  side  of  the 
engine.  Referring  to  Figs.  37  and  38  it  will  be  seen  that 
the  link  block  is  shown  in  the  centre  of  the  link.  It  is  evi- 


no 


COMPOUND    LOCOMOTIVES. 


dent  that  if  the  reverse  shaft  be  dropped  from  the  position 
shown,  the  block  in  the  slot  in  the  reverse  shaft  arm,  as 
well  as  the  upper  end  of  the  link  hanger,  will  be  pulled,  by 
means  of  the  horizontal  link  attached  to  the  bracket,  to  a 


FIG.  38. 
Heintzelman   Gear. 

position  further  to  the  left,  or  toward  the  end  of  the  reverse 
shaft  arm,  than  is  shown.  Meantime,  the  upper  end  of  the 
link  hanger  on  the  other  side  of  the  engine  has  remained  at 
the  same  distance  from  the  centre  of  the  reverse  shaft.  The 
effect  of  dropping  the  horizontal  reverse  shaft  arm  to  the 
lowest  position  to  put  the  engine  in  full  forward  gear,  is  to 
bring  the  upper  ends  of  both  link  hangers  in  the  same  rela- 
tive position  with  respect  to  the  reverse  shaft,  and  give  the 
same  cut-off  in  both  cylinders  in  full  forward  gear.  At  all 
other  positions  of  the  link,  the  block  in  the  reverse  shaft  on 
the  h.  p.  side  is  nearer  the  centre  of  the  reverse  shaft,  and 
the  effect  is  the  same  as  if  a  shorter  reverse  shaft  arm,  and 
one  of  variable  length,  was  used  on  the  h.  p.  side.  In  this 
way  the  1.  p.  link  is  lower  than  the  h.  p.  link,  for  all  cut-offs 
except  that  of  full  forward  gear,  hence  the  cut-off  is  longer 


VALVE    GEAR    ADJUSTMENTS. 


Ill 


in  the  1.  p.  cylinder  than  in  the  h.  p.  The  effect  of  this 
device  on  the  distribution  of  steam  power  in  the  cylinders 
and  on  the  relative  cut-offs  is  given  in  Table  P. 

TABLE  P. 

Heintzelman     djustment  of  Cut-off  and  Per  Cent,  of  Power  in  H.  P. 
and  L.  P.  Cylinders.     See  Appendix  R. 


Cut-off  h.  p. 
cylinder,  inches. 

Cut-off  1.  p. 
cylinder,  inches. 

Per  cent,  of  total  work 
done  in  h.  p.  cylinder. 

Per  cent,  of  total  work 
done  in  1.  p.  cylinder. 

233A 
•2.^/2 
205/8 

15 
I2& 

9H 

23^ 
227/8 
2l7/8 
I8# 
17 
15 

4I-I5 
43-18 
41.64 
46.28 

45-04 
49.08 

58.85 
56.82 
58.36 
53-72 
54.96 
50.92 

76.  The  Rogers  Locomotive  Works  Link  Hanger 
Adjustment. — The  Rogers  Locomotive  Works  have  used  a 
link  hanger  in  two  parts,  each  part  being  provided  with 
teeth  to  prevent  slipping.  In  this  way  the  bolts  can  be 
loosened  and  the  link  hanger  be  made  longer  or  shorter  as 
desired. 

76a.  Different  Adjustments  of  Cut-Offs  That  Have 
Been  Used  for  Compound  Locomotives. — Mr.  von  Borries 
from  his  experience  has  finally  settled  on  the  following  ratio 
of  cut-offs  in  the  h.  p.  and  1.  p.  cylinders  as  being  in  his 
opinion  best  adapted  for  average  work.  See  Fig.  27. 

Cut-off  H.  P.  Cylinder,  per  cent.    30     40     50     60     70     78 
L.  P.          "  "  40     50     58     65     73     80 

After  a  number  of  experiments  Mr.  Joseph  Lythgoe,  of 
the  Rhode  Island  Locomotive  Works  has  decided  to  use 
\Ytf  in.  outside  lap  on  the  h.  p.  cylinder,  and  %  in.  lap  on 
1.  p.  cylinder.  This  gives  about  3^  in.  later  cut-off  in  the 
1.  p.  cylinder  for  a  24  in.  stroke,  and  it  is  believed  will  so 
satisfactorily  adjust  the  cut-offs  that  a  change  in  the  length 
of  the  link  hanger  will  not  be  needed.  This  plan  has  the 
advantage  of  giving  the  same  relative  cut-offs  in  both  cylin- 
ders whether  the  engine  is  going  ahead  or  backing.  The 
valve  travel  used  with  this  amount  of  outside  lap  is  6j^  ins. 


112 


COMPOUND    LOCOMOTIVES. 


TABLE  Q. 

Giving  details  of  Valve  Movement  and  Port  Openings  on  Dean  Compound. 
Locomotive  on  Old  Colony  R.  R.  Cylinders  20  in.  and  28  in.  X  24  in.  Drivers 
6g  in.  Diameter.  Valve  Travel  6%  in.  Outside  Lap  i  in.  Inside  Clearance 
or  Negative  Lap  %  in.  See  Appendix  R. 


h.  p 

Cut-off  Cut 


20% 
18 

16 

13% 


9i96 

20% 

17% 


12 

9i-i 


l.  P. 

off 


21 


1  9  iV 


14% 

12% 


17% 
15% 


"X 

10% 


h.p. 
Lead. 


A 


A 


I.P. 

Lead. 


61! 


/o 


h.  p. 
Release. 


22^8 

21% 

20% 

19 

17% 


i5X 

22% 
21 
20  A 


Release. 


22% 
20% 


17  A 

22% 

21 H 

20|f 

I9X 
18% 


h.  P. 

Compres- 
sion. 


23A 


22; 

22 
2IJ 

20; 


23% 
22H 
22  ^ 


20X 


l.p. 

Compres- 


23A 

23 

22% 

22% 

21  H 

21% 

20% 

23% 
22}| 
22% 
22% 


20% 


Port 

Opening, 
h.  p. 


Port 

Opening. 
1.  p. 


2% 

I 


y 
H 


TABLE    R. 

Giving  Details  of  Valve  Movement  and  Port  Openings  on  Dean  Compound 
Locomotive  on  Lehigh  Valley  R.  R.  Cylinders  20  in.  and 30  in.  X  24  in.  Drivers 
jo  in.  Diameter.  Valve  Travel  h.  p.  5  in.,  I.  p.  6%  in.  Outside  Lap  h.  p.  %. 
in.,  1.  p.  /%  in.  Inside  Clearance  or  Negative  Lap  h.  p.  T3g  in.,  I.  p.  o  in.  See 
Appendix  R. 


w 


h.  p. 
Cut-off  Cut'-off 


20 

18 
16 


17 


19% 


19% 
18% 

17% 
16% 


h.  p. 

Lead. 


V 

X 
A 

X 

H 

U 
iii 


i.  p. 

Lead. 


Line 

I 

Line 


h.  p. 

Release. 


22% 
21% 
20% 

19% 
18% 

I7K 

22% 
21% 
21% 
20^ 

19 II 


Release. 


22% 


20% 

19 


22{| 
22% 

2IJ1 
21% 
20% 


h.p. 

Compres- 
sion. 

23 
22% 

21 H 
20% 
20 
19 

22  it 

22X 


l.p. 

Compres- 


22 A 

2I-lV 
20% 

19% 

16% 

22^ 
21% 
21% 

20^ 
20 


h.p. 

Port 

Opening. 


I}7! 
iS 


l.p. 

Port 

Opening. 


H 


A 


VALVE    GEAR    ADJUSTMENTS, 


I  I 


TABLE  S. 

Giving  the  Steam  Port  Openings  of  Schenectady  (Pitkin)  Compound  Locomo- 
tive on  Chicago  dr>  North-Western  R.  R.  Cylinders  20  in.  and 30  in.  X  24  in. 
Drivers  68  in.  Diameter.  Valve  Travel  6%  in.  Outside  Lap  1%  in.  Inside 
Clearance  or  Negative  Lap,  h.  p.  %  in.,  1.  p.  ^  in. 


h.  p.  cyl. 
Cut-off  Inches. 


Cut-off  Inches. 


h.  p.  cyl. 
Lead,    Inches. 


1.  p.  cyl. 
Lead,    Inches. 


h.  p  cyl. 

Valve    Opening, 

Inches. 


1.  p.  cyl. 

Valve    Opening, 

Inches. 


Front 


Stroke.  Stroke. 


I9if 
*4iV 


Back 


Front 


Stroke-  Stroke. 


i9rY 


Back 


Front 


Stroke.  Stroke. 


20f| 
20#' 

I6H 

14" 

12 


iftr" 


Back 


Front 


Stroke.  Stroke. 


Back 


Front 


Stroke.    Stroke. 


H" 


Back 


H" 


Front 


Stroke.    Stroke. 


it" 
H* 

H" 


Back 


W 


H1 


TABLE  T. 

Giving  the  Steam  Port  Openings  of  the  Schenectady  Compound  Locomotive 
on  Adirondack  &°  St.  Lawrence  R.  R.  Cylinders  iq  in.  and  28  in.  X  24  in. 
Drivers,  6q  in.  diameter.  Valve  Travel,  6%  in.  Outside  Lap,  il/fa  in.  Inside 
Clearance  or  Negative  Lap  h.  p.,  ^  in.  ;  1.  p.,  fa  in.  See  Appendix  R. 


h.  p.  cyl. 
Cut-off, 
Inches. 


1.  p.  cyl. 
Cut-off, 
Inches. 


h.  p.  cyl. 
Lead,  I 


nches. 


1.  p.  cyl. 
Lead,  Inches. 


h.  p.  cyl. 

Valve  Opening, 

Inches. 


1.  p.  cyl. 

Valve  Opening, 

Inches. 


Front 
Stroke 


Back 
Stroke 


Front 
Stroke 


Back 
Stroke 


Front 
Stroke 


Back 
Stroke 


Front 
Stroke 


Back 
Stroke 


Front 
Stroke. 


Back 
Stroke 


Front 
Stroke. 


Back 
Stroke. 


20  iV 

i9Ty; 

Mil" 

"A* 


20  & 
I9H 


12 


20^ 
20" 

18" 
16" 
14" 
12" 


A 


H 


H 


H"      H" 


TABLE  U, 

Giving  the  Steam  Port  Openings  of  Schenectady  Compound  Locomotive  on 
Adirondack  6°  St.  Lawrence  R.  R.  Cylinders,  22  in.  and  32  in.  X  26  in. 
Drivers,  51  in.  diameter.  Valve  travel,  5^  in.  Outside  Lap,  %  in.  Inside 
Clearance  or  Negative  Lap,  o  in.  See  Mppendix  R. 


h.  p.  cyl. 
Cut-off, 
Inches. 

1.  p.  cyl.      ' 
Cut-off, 
•    Inches. 

h.  p.  cyl. 
Lead,  Inches. 

1.  p.  cyl. 
Lead,  Inches. 

h.  p.  cyl. 
Valve  Opening, 
Inches. 

1.  p.  cyl. 
Valve  Opening, 
Inches. 

Front 
Stroke 

Back 
Stroke 

Front 
Stroke 

Back 
Stroke 

Front 
Stroke 

Back 
Stroke 

Front 
Stroke 

Back 
Stroke 

Front 
Stroke. 

Back 
Stroke. 

Front 
Stroke 

Back 
Stroke. 

23iV 

20  X" 

I7M" 
I4H* 

12^" 
10" 

23^" 
20^" 

i73T 

I4H" 

12^" 

9^" 

23^" 
21  " 
19" 
17" 
15" 
13" 

23H" 
21/8" 

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114 


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Appendix  R. 

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VALVE    GEAR    ADJUSTMENTS. 


117 


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VALVE    GEAR    ADJUSTMENTS, 


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* 


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120 


COMPOUND    LOCOMOTIVES. 


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VALVE    GEAR    ADJUSTMENTS, 


121 


TABLE  V. 

Showing  the  Change  in  Exhaust  Closure  Affected  by  Using  Inside  Clearance 
or  Negative  Lap.  Taken  from  a  Schenectady  10  Wheeler  on  the  Michigan 
Central  R.  R.  19  in.  X  24  in.  Single  Expansion  Engine  and  20  and  29  X 
24  in.  Compound  Engine.  See  Appendix  R. 


Negative 
Lap  or 
Clearance, 
Inches. 

Cut-off, 
per  cent. 

Compound. 

Single  Expansion. 

Release 
of  Steam 
per  cent, 
of  Stroke. 

Compres- 
sion 
of  Steam 
per  cent, 
of  Stroke. 

*  Valve 
Travel  and 
Outside 

Inches. 

Release 
of  Steam, 
per  cent, 
of  Stroke. 

Compres  • 
sion 
of  Steam 
per  cent 
of  Stroke. 

Valve 
Travel  and 
Outside 
Lap, 
Inches. 

•J 
•f 

"I 
«l 

33 
41.7 

50 
58-5 
83-5 

33 
41.7 
50 
58-5 
83-5 

33 
41.7 

50 
58.5 
83.5 

33 
41.7 
50. 
58.5 
8*.S 

74-4 
78.1 
81.2 
84.4 
94-8 

70.8 

73-5 
78.1 
81.2 
93-7 

67.1 
70.8 
75-5 
79-7 
92.9 

63.0 
67.7 
72-9 
77-6 

QI.Q 

80.0 
82.9 

85-4 
88.5 

96.3 

82.3 

85.4 
87.5 
89.6 
96.9 

86.1 
88.0 
90.  i 
92.2 
97-7 

88.0 
90.1 
92.2 
93-8 
Q7.Q 

6K 
I# 

6K 
i^ 

6^ 

ilA 

6K 
I* 

62.5 
66.7 
73.9 

79-2 
92.7 

80.2 
82.3 
87.5 
90.6 
96.9 

5M 
% 

CHAPTER    XII. 

MAIN   VALVES. 

77.  Lap,  Travel  and  Size  of  Ports. — The  dimensions 
of  the  steam  ports,  valve  travel,  and  outside  and  inside 
lap,  suitable  for  compound  locomotives,  do  not  differ  much 
from  the  best  practice  for  single  expansion  locomotives,  but 
it  has  been  abundantly  proved  that  better  valve  motions  are 
needed  for  compound  locomotives  than  are  ordinarily 
used  for  single  expansion.  Also  the  valves  and  ports  should 
be  always  in  proportion  to  the  cylinders,  and  this  gives  to 
the  valves  of  the  1.  p.  cylinders  very  large  dimensions.  The 
largest  port  in  common  use  a  few  years  since  was  19  inches. 
Now  the  1.  p.  cylinders  of  compound  locomotives  have  ports 
24  inches  long.  Probably  the  compulsory  use  of  longer 
ports  and  larger  valves  has  had  more  to  do  with  the  recent 
tendency  to  use  piston  valves  than  any  other  factor.  Large 
slide  valves  of  the  ordinary  D  form  are  very  difficult  to  bal- 
ance satisfactorily,  and  they  cause  a  much  increased  wear  on 
the  eccentrics  and  links. 

78.  Piston  Valves.  —  Piston  valves  are  necessarily  baU 
anced  from  the  nature  of  their  construction,  and  certainly 
have  been  shown  to  be  quite  as  applicable  to  locomotive 
work  as  to  marine  work,  where  they  are  now  so  commonly 
used.  With  a  piston  valve  a  very  long  port  is  readily  ob- 
tained, and  in  fact  a  larger  port  is  necessary,  as  the  same 
length  of  port  on  the  circumference  of  a  piston  valve  is  not 
as  effective  as  a  rectilinear  port  of  the  ordinary  form  with 
a  flat  valve. 

Two  express  locomotives  with  piston  valves  have  been 
built  by  Mr.  von  Borries  for  the  German  State  Railroads. 
The  experience  with  these  engines  shows  that  a  piston  valve 


MAIN    VALVES.  123 

must  be  considerably  longer  in  circumference,  which  is  in 
reality  the  length  of  the  port,  than  is  required  with  a  flat 
valve  to  give  equally  good  admission  of  steam.  Ample 
room  must  be  provided  for  the  approach  of  steam  to  a  piston 
valve  or  the  advantage  of  its  longer  port  will  not  be  gained. 
Piston  valves  should  have  the  same  travel,  and  inside  and 
outside  lap  as  the  ordinary  form  of  D  slide  valves.  The 
piston  valve  is,  in  fact,  only  a  slide  valve  rolled  up  to  form 
a  cylinder,  and  needs  the  same  treatment  in  design. 

79.  Some  Effects  of  Inadequate  Valve  Motions.— 
The  greatest  evils  which  have  to  be  met  in  arranging 
steam  valves  for  compound  locomotives  are  those  of  wire- 
drawing and  compression.  The  wire-drawing  in  the  h  p. 
cylinder  is  practically  no  worse,  nor  more  detrimental,  than 
in  a  single  expansion  engine,  but  wire-drawing  into  the  1.  p. 
cylinder  causes  additional  loss,  and  interferes  with  the 
adjustment  of  the  power  between  the  cylinders  by  means  of 
the  cut-off.  In  some  compounds  already  built  the  wire- 
drawing through  the  main  valve  for  the  1.  p.  cylinder  is  so 
great  that  the  cut-off  point  is  not  perceivable  on  the  indi- 
cator card,  and  the  engine  works  in  about  the  same  way  as 
the  old  fashioned  stationary  engine  with  a  throttle  governor. 

Compression  causes  more  loss  of  power  and  efficiency  in 
the  h.  p.  than  in  the  1.  p.  cylinder  on  account  of  the  higher 
back  pressure.  In  the  1.  p.  cylinder  the  absolute  back 
pressure  at  the  time  of  exhaust  closure  is  not  far  from  20 
pounds,  and  with  five  compressions  the  terminal  pressure  at 
the  end  of  the  stroke  would  be  not  far  from  100  pounds 
absolute.  But  in  the  h.  p.  cylinder  the  absolute  back  pres- 
sure is  ordinarily  about  65  pounds  and  with  five  compressions 
the  pressure  at  the  end  of  the  stroke  in  the  h.  p.  cylinder 
would  be  nearly  300  pounds,  or  very  much  above  boiler  pres- 
sure, 6.  What  actually  does  occur  is  this  :  when  compound 
locomotives  with  the  ordinary  valve  gear  are  running  at  a 
short  cut-off  and  at  high  speed,  the  compression  in  the  h.  p. 


124  COMPOUND    LOCOMOTIVES. 

cylinder  rises  to  a  point  above  the  boiler  pressure,  where  it 
lifts  the  main  valve,  and  the  excess  of  steam  in  the  clearance 
spaces  and  ahead  of  the  piston  is  pushed  into  the  steam 
chest.  This  will  be  observed  in  Figs,  n,  12,  14,  15,  112, 
113,  127,  136  and  149. 

Whether  a  piston  valve,  or  a  slide  valve  of  the  ordinary 
kind  is  used,  the  simplest  way  to  reduce  wire-drawing  and 
compression  after  making  the  ports  as  long  as  is  practi- 
cable, is  to  increase  the  valve  travel,  increase  the  outside 
lap,  and  cut  out  the  valve  on  the  inside  to  give  what  is  called 
"clearance"  or  "negative"  lap.  See  Table  Ui. 

The  effect  of  increasing  the  valve  travel  and  outside  lap, 
is  to  give  a  greater  port  opening  at  short  cut-offs  and  to 
postpone  the  point  of  compression  toward  the  end  of  the 
stroke,  thus  reducing  compression.  The  effect  of  cutting 
out  the  inside  of  the  valve  to  make  a  negative  lap  is  to  delay 
the  closure  of  the  exhaust  and  reduce  compression. 

80.  Effect  of  Long  Valve  Travel  and  Inside  Clear- 
ance or  Negative  Lap. — The  following  will  illustrate  the 
benefit  obtained  from  a  change  in  valve  travel,  outside  lap, 
and  from  the  use  of  inside  negative  lap:  A  5^  inch  travel 
with  ^  outside  lap  will  give  about  -^  inch  port  opening  at 
25  percent,  cut-off.  A  7  inch  travel  and  i%  inches  outside 
lap  will  give  nearly  y2  inch  port  opening  at  the  same  cut-off. 
fyfa  inch  negative  lap  will  reduce  compression  to  a  point 
somewhat  below  the  admission  pressure,  which  is  where  it 
should  be,  when  used  on  an  engine  which  formerly  had 
positive  inside  lap,  and  a  compression  much  above 
boiler  pressure  before  the  completion  of  the  stroke.  7 
inches  valve  travel  on  a  locomotive  is  not  so  great  as  to 
lead  to  any  mechanical  difficulties  in  operation  or 
design.  This  has  been  conclusively  shown  by  the  experi- 
ence of  Mr.  L.  B.  Paxson,  S.  M.  P.,  of  the  Philadelphia 
&  Reading  Railroad,  Figs.  39  to  42,  and  by  the  experi- 
ence of  the  Rhode  Island  Locomotive  Works.  These  two 


MAIN    VALVES.  125 

companies  have  led  in  this  country  in  the  matter  of  long 
valve  travel.  As  much  as  ^  inch  negative  lap  on  each  side 
on  the  h.  p.  cylinder  has  been  used  with  success  on  high 
speed  compound  locomotives.  ^  inch  negative  lap  on  each 
side  has  been  used  with  success  on  the  1.  p.  cylinder.  -^ 
inside  negative  lap  has  been  used  with  excellent  results  on 
single  expansion  locomotives,  and  the  experience  already 
had  shows  beyond  doubt  that  inside  clearance  is  absolutely 
necessary  on  all  high  speed  locomotives,  whether  single 
expansion  or  compound,  if  the  best  results  are  desired.  It 
is  practically  impossible  to  design  a  high  speed  compound 
locomotive,  no  matter  what  the  type,  that  will  run  without 
excessive  wire-drawing  and  compression  with  the  Stephenson 
link  motion  or  with  any  of  the  commonly  used  locomotive 
valve  gears,  without  using  a  long  valve  travel  and  considerable 
inside  clearance  or  negative  lap  for  both  cylinders.  The 
greater  amount  of  negative  lap  is  needed  for  the  h.  p. cylinder. 
The  effect  of  inside  clearance  or  negative  lap  on  steam 
distribution  at  various  low  speeds,  and  the  effect  it  has  on 
the  shape  of  indicator  cards,  is  shown  by  Fig.  43,  indicator 
cards  Nos.  I  to  6.  The  data  for  these  cards  is  given  in  Table 
W.  It  will  be  noticed  that  at  low  speeds  the  steam  from 
the  exhaust  of  one  end  of  the  cylinder  passes  over  into 
the  other  end  of  the  cylinder  through  the  opening  that  is 
made  between  the  two  ends  of  the  cylinders  by  the  use  of 
negative  lap.  The  negative  lap  in  this  case  was  -^  and  T36 
inches.  From  card  No.  6  it  is  clear  that  this  transfer  of  steam, 
at  the  time  of  exhaust  from  one  cylinder  to  the  other,  dis- 
appears almost  entirely  when  speed  has  increased  to  32.5 
miles  per  hour.  These  cards  also  show  that  the  engine  from 
which  they  were  taken  had  liberal  steam  pipes  and  passages, 
as  the  steam  chest  pressure  and  receiver  pressure  varies 
but  little  from  the  pressure  at  admission.  These  are  admir- 
able cards  from  a  compound  locomotive  for  the  speed  at 
which  they  were  taken. 


126 

f 


COMPOUND    LOCOMOTIVES. 


FIG.  39. 
Inch  Inside  Lap. 


FIG.  40. 
Inch  Negative  Lap. 


6 


FIG.  41.  FIG.  42. 

Inch  Inside  Lap.  1A  Inch  Negative  Lap. 

Indicator  Cards  Showing  the  Effect  of  Negative  Lap. 


MAIN    VALVES. 


127 


B.Pt 


63 


5  _. 


No  61 


No  50          £, 


No  76 


FIG.  43. 

Indicator  Cards  from  Compound  Locomotive  Showing  Effect  of 
Negative  Lap  at  Low  Speed. 


128 


COMPOUND    LOCOMOTIVES. 


TABLE  W. 

Giving  Data  about  Indicator  Cards  Nos.  i  to  6,  Fig.  43,  from  Schenectady 
{Pitkin}  Compound  on  the  Michigan  Central  Railroad.     See  Appendix  R. 


Number  of 
Card. 

Revolution 
per  minute. 

Miles  an  hour. 

Cut-off  in  Inches. 

H.  P.           L.  P. 

I 

40 

6.8 

21%                22% 

2 

72 

12.2 

17           isy& 

3 

104 

17-6 

13^         151^ 

4 

108 

18.3 

12                      13}^ 

5 

104 

I7.6 

10%                I2^i 

6 

192 

32-5 

10%                I23/& 

Length  of  Valve  Travel                                                                 6^  in.  full  gear. 

"    Steam  Ports,  1.  p.  cyl.     -                                                                 20" 

"         "          "      h.  p.  cyl.                                                                -     18" 

Width  of          "          "      1.  p.  cyl.     -                                                                   2%" 

"       "          "          "      h.  p.  cyl.                                                                -       2^" 

Outside  Lap,  h.  p.  cyl.                                    -             -             -                            i%" 

Inside  Clearance,  h.  p.  cyl.                                                  -                          -         tV 

Outside  Lap,  1.  p.  cyl.                                                   -                          -              il/%" 

Inside  Clearance,  1.  p.  cyl.                                                  ...         T^" 

Giving  data  regarding  Figs.  $g  and  41,  cards  Nos.  i  to  6,  taken  from  a 
Philadelphia  &*  Reading  express  engine,  with  Single  Expansion  cylinders. 


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The  small  effect  of  a  little  inside  clearance  or  negative 
lap  is  very  clearly  and  satisfactorily  shown  by  Figs.  39,  40, 
41,  and  42,  indicator  cards  Nos.  i  to  6,  which  were  taken 
from  a  21  x  22  inch  Philadelphia  &  Reading  express  loco- 


MAIN    VALVES. 


129 


TABLE  Y. 

>  K 

Giving  data  regarding  Figs.  40  and  42,  cards  Nos.  i  to  7,  taken  from  a 
Philadelphia  6°  Reading  express  engine,  with  single  expansion  cylinders,  and 
showing  the  small  effect  produced  by  a  little  inside  clearance  or  negative  lap,  also 
showing  the  need  of  much  inside  clearance,  and  showing  also  the  slight  effect  on 
steam  distribution  produced  by  inside  clearance  at  slow  speed. 


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FIG.  44. 
Good  Steam  Distribution  in  Single  Expansion  Locomotive  Cylinders. 

motive.  The  normal  boiler  pressure  is  145  pounds  by  gauge. 
Tables  X  and  Y  give  the  data  about  these  cards.  This 
engine  is  unusual  in  having  7  inches  valve  travel  and  I  ^  in. 
outside  lap.  Probably  these  indicator  cards  are  the  best 
ever  taken  from  a  locomotive  with  a  Stephenson  link 
motion.  The  good  points  of  such  a  card  as  No.  7,  Table 
Y,  Fig.  44,  taken  from  this  engine  with  %  mcn  negative 
lap,  at  70  miles  an  hour  show  how  difficult  it  will  be  for  a 
compound  locomotive  to  make  a  saving  in  passenger  service 
against  a  locomotive  having  long  valve  travel  and  inside 
clearance  and  ample  area  of  steam  and  exhaust  ports.  The 
effect  of  using  inside  clearance  on  the  distribution  of  steam 


I3O  COMPOUND    LOCOMOTIVES. 

at  slow  speed  is  very  small,  as  is  clearly  shown  by  a  com- 
parison of  Figs.  39  and  41,  with  Figs.  40  and  42.  These 
cards,  taken  with  the  throttle  full  open,  show  that  consider- 
able inside  clearance  is  needed  to  produce  a  substantial 
benefit  at  high  speed  with  long  valve  travel.  The  ^  inch 
inside  clearance  used  on  this  engine  would  have  shown  a 
more  substantial  change  in  mean  effective  pressure  at  high 
speed-  if  the  valve  travel  had  been  5^  inches,  as  is  common 
on  locomotives.  The  new  compound  locomotive  designed 
by  Mr.  Axel  S.  Vogt,  Mechanical  Engineer  of  the  Pennsyl- 
vania Railroad,  has  ^  inches  inside  clearance  in  the  h.  p. 
cylinder  and  $/%  inches  in  the  1.  p.  valve,  and  7  inches  valve 
travel. 

81.  Conclusions  about  Main  Valve  Dimensions. — It 
is  impossible  to  give  a  general  rule  for  the  area  of  steam 
ports  and  valves  of  compound  locomotives.  What  can  be 
said  that  is  useful  is  :  the  valve  travel  should  be  as  long  as 
it  can  be  made  without  inducing  mechanical  difficulties.  It 
probably  should  never  be  less  than  6  inches  and  would 
better  be  7  inches.  The  inside  clearance  or  negative  lap 
should  be  what  is  necessary  to  reduce  compression,  and  the 
increase  of  the  negative  lap  should  be  carried  on  until  the 
indicator  cards  from  the  engines  under  normal  conditions 
are  comparatively  satisfactory  in  the  matter  of  compression. 
If  there  is  any  waste  due  to  negative  lap,  it  will  show  on 
the  indicator  card,  and  can  be  estimated  therefrom  and  in  no 
other  way  except  by  an  elaborate  shop  test.  There  is  a  tra 
dition  among  railroad  men  which  has  operated  against  the 
proper  use  of  negative  lap.  This  tradition  is  to  the  effect 
that  inside  clearance  causes  a  waste  of  steam,  but  this 
tradition  is  not  founded  on  fact  and  is  true  only  for  very 
slow  speed  locomotives. 

In  conclusion,  about  all  that  can  be  said  to  assist  the 
designer  is  that  the  best  modification  that  can  be  made  of 
the  common  form  of  link  motion  will  be  none  too  good  for 


MAIN    V'ALVES.  13! 

compounds,  and  it  is  well  worth  while  to  pay  a  considerable 
sum  to  get  long  valve  travel  and  large  steam  ports.  If  the 
steam  ports  are  made  the  same  length  for  both  h.  p.  and 
1.  p.  cylinders  and  are  made  considerably  longer  than  the 
diameter  of  the  h.  p.  cylinders,  say  20  per  cent,  and  the 
valve  travel  for  the  common  sizes  of  locomotives  is  made 
from  6y2  to  71^  inches,  and  the  negative  lap  about  ^ 
inches  for  freight  and  ^  inches  for  passenger  for  the  1.  p. 
cylinder,  and  ty&  of  an  inch  for  freight  and  ^  inches  for 
passenger  for  the  h.  p.  cylinder,  the  practical  results  from 
service  will  be  pretty  nearly  satisfactory.  If  the  compres- 
sion with  these  proportions  is  too  great,  as  it  may  be  for 
high  speeds,  the  negative  lap  must  be  increased.  If  there 
is  too  much  wire-drawing,  there  is  only  one  recourse  with 
the  Stephenson  link,  namely,  to  increase  valve  travel  and 
the  length  of  the  ports.  Of  course,  the  supplementary 
or  Allan  port  is  an  advantage,  but  does  not  give  as  much 
benefit  as  an  increase  of  valve  travel.  To  add  an  Allan 
port  to  long  travel  valves  sometimes  causes  trouble  in 
design,  as  the  valve  must  be  longer  and  the  area  to  be 
balanced  will  be  larger.  Allan  ports  for  piston  valves  are 
scarcely  practical,  as  the  same  effect  can  be  gained  by 
making  the  valve  with  a  larger  diameter,  and  this  is  easier 
and  simpler  than  to  introduce  the  additional  packing  rings 
for  the  Allan  port.  In  these  remarks  all  consideration  of 
the  unusual  forms  of  valve  gears  so  far  tried  have  been 
omitted  for  the  reason  that  none  of  them  have  proved  to  be 
what  is  wanted  for  practical  work. 


CHAPTER    XIII. 

STEAM    PASSAGES  — ACTION    OF    EXHAUST. 

82.  Size  of  Steam  Passages  and  Loss  Due  to 
Wire-Drawing. — All  of  the  rules  applicable  to  the  use  of 
steam,  so  far  as  steam  passages  are  concerned,  that  are 
common  in  stationary  engine  work  apply  with  equal  force 
to  locomotives.  Formerly  it  was  a  common  defect  in  loco- 
motives to  have  too  small  steam  passages,  but  now  a  few 
of  the  modern  designs  have  the  same  area  of  passages  as 
are  provided  for  stationary  engines.  When  this  is  done, 
and  the  engine  is  run  with  a  wide-open  throttle,  the 
difference  in  pressure  between  the  boiler  and  the  steam 
chest  will  be  very  small,  even  when  the  locomotive  is  run- 
ning at  considerable  speed.  See  Figs.  43,  46  and  47. 

The  loss  due  to  running  a  locomotive  with  a  partly  open 
throttle  or  with  too  small  steam  passages  is  more  than  is 
generally  understood,  as  has  been  recently  proved  by  the 
shop  tests  of  a  locomotive  by  Professor  Goss  at  the  Purdue 
University.  Diagram,  Fig.  45,  shows  in  a  general  way  what 
these  results  indicated.  Such  wire-drawing  as  is  shown  on 
the  diagram  gave  considerable  super-heat  to  the  incoming 
steam,  but  the  reduction  in  cylinder  condensation  due  to 
super-heat  did  not  offset  the  loss  in  potential  of  steam 
pressure.  Therefore,  it  may  be  concluded  that  locomotives 
should  have  large  steam  passages  and  be  run  with  a  wide- 
open  throttle  ;  more  particularly  is  this  true  of  the  com- 
pound locomotive,  which  depends  for  its  economy  upon  the 
utilization  of  the  high  potential  of  increased  steam  pressure 
by  giving  greater  expansion. 

132 


STEAM    PASSAGES— ACTION    OF    EXHAUST.  133 


.  so 

I 

a* 

i 
$ 

^4     30 


O 

\o 


O  ^>- 


J)!?]  PIPE  PRESSURE 

FIG.  45. 
Diagram  Showing  Loss  of  Efficiency  Due  to  Wire-Drawing  Through  Throttle. 


FIG.  46. 

Indicator  Cards  Showing  Difference  Between  Boiler,  Steam  Chest 
and  Initial  Pressures. 


134 


COMPOUND    LOCOMOTIVES. 


FIG.  47. 

Indicator  Cards  Showing  Difference  Between  Boiler,  Steam  Chest 
and  Initial  Pressures. 


FIG.  48. 

Indicator  Cards  Showing  Effect  of  Small  Nozzles  on  Back  Pressure. 
See  Table  AA. 


STEAM    PASSAGES— ACTION    OF    EXHAUST. 


135 


The  variation  in  steam  chest  pressure  of  locomotives, 
where  the  throttles  are  of  proper  dimensions,  and  the  steam 
pipes  and  passages  are  adequate,  is  shown  by  Figs.  46  and 
47,  Cards  Nos.  I  to  II,  Table  Z,  which  were  taken  from 
a  1 6  X  24  passenger  engine  on  the  Chicago,  Milwaukee  and 
St.  Paul  road.  The  small  drop  between  the  boiler  and  the 

TABLE  Z. 

Showing  the  Variation  in  Steam  Chest  Pressure  on  a  Single  Expansion 
Locomotive,  illustrating  the  comparatively  small  drop  between  the  Boiler  and  the 
Steam  Chest  at  a  speed  not  exceeding  45  miles  per  hour,  when  the  throttle  is  wide 
open.  See  Figs.  46  and  47. 


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36.5 

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138 

steam  chest  in  this  case  is  due  to  a  wide-open  throttle.  At 
high  speeds  the  drop  increases  somewhat  depending  upon 
the  cut-off  and  the  size  of  the  passages,  but  these  cards 
show  what  may  be  expected  in  fairly  well  designed  loco- 
motives at  a  speed  not  exceeding  240  revolutions  per 
minute,  which  in  this  engine  amounts  to  about  44  miles  per 
hour.  The  engine  is  a  16  X  24  inch  cylinder,  five-foot 
wheel  passenger  locomotive  of  the  eight-wheel  American 
type. 

83.  Effect  of  Exhaust  on  Fire  and  on  Back  Pres- 
sure.—  The  lower  pressure  and  greater  volume  of  the 
exhaust  from  the  compound  locomotive  appears  to  produce 


136 


COMPOUND    LOCOMOTIVES. 


a  more  uniform  and  a  better  effect  on  the  fire.  This 
advantage,  added  to  the  decrease  in  the  total  fuel  con- 
sumption per  minute,  resulting  from  the  saving  of  the 
compound,  has,  so  far  as  can  be  seen,  caused  a  secondary 
saving  of  fuel  due  to  compounding.  There  are,  then, 
perhaps,  two  savings  due  to  compounding.  The  primary 
saving  due  to  the  compounding  per  se,  and  the  secondary 
resulting  from  the  better  action  of  the  draft  and  the 
decreased  forcing  of  the  fires,  142. 

In  suburban  or  elevated  railroad  service,  where  mufflers 
are  put  on  the  exhaust  pipe  of  single  expansion  engines  to 
decrease  the  noise  of  the  exhaust,  the  use  of  the  compound 
locomotive,  with  its  lower  pressure  of  exhaust,  enables  the 
mufflers  to  be  dispensed  with.  In  this  way  as  much  as  20  per 
cent,  of  steam  may  be  saved  by  the  reduction  of  the  back 
pressure  in  the  cylinders  caused  by  the  mufflers.  Mufflers 
clog  up  quickly  and  have  to  be  bored  out  frequently,  or  the 
back  pressure  becomes  so  great  as  to  make  the  engines 
"logy,"  139-14:7. 

TABLE  AA. 

Back  Pressure  Before  Changing  Valves  and  Nozzles. 


No.  of 
Card. 

Speed. 
Miles 
per  hour. 

Cut-off. 

Boiler 
Pressure. 
Pounds. 

Initial 
Pressure. 
Pounds. 

Mean 
Effective 
Pressure. 
Pounds. 

Mean  Back  Pressure  includ- 
ing Compression.     Pounds. 

4 

15- 

12" 

160. 

151. 

98. 

20.5 

I 

24. 

9" 

160. 

ISO. 

79- 

22.5 

2 

30. 

8" 

160. 

143. 

57- 

25-5 

5 

35- 

8" 

I58. 

135- 

5i- 

27. 

3 

42. 

8" 

1  60. 

150. 

57- 

31-5 

6 

53- 

5" 

160. 

146. 

39- 

28. 

Figs.  48  and  49  show  the  need  of  very  carefully  watch- 
ing the  details  of  a  new  design  of  engine,  by  examining 
indicator  cards,  to  prevent  losses  in  the  cylinders  by 
back  pressure.  Fig.  48,  Indicator  Cards  Nos.  I  to  6,  see 
Table  AA,  gives  the  back  pressure  in  a  ten-wheel  engine 
with  a  3^  exhaust  nozzle  double,  that  is,  with  a  separate 
nozzle  for  each  cylinder.  The  nozzles  were  increased  in 


STEAM    PASSAGES— ACTION    OF    EXHAUST. 


137 


diameter  -J  of  an  inch,  and  the  inside  lap  was  cut  out  from 
^ig  on  both  sides  to  -^  negative  lap  on  both  sides.  The 
decided  reduction  in  back  pressure,  as  shown  by  Fig.  49, 
Cards  Nos.  I  to  6,  and  by  Table  BB,  changed  the  engine 


BP 


a './? 


FIG.  49. 

Indicator  Cards  Showing  Decrease  of  Back  Pressure  Following  an 
Increase  of  the  Diameter  of  Exhaust  Nozzle.     See  Table  BB. 

TABLE   BB. 
Back  Pressure  after  Changing  Valves  and  Nozzles. 


No.  of 
Card. 

Speed, 
Miles  per  hour. 

Cut-off. 

Boiler 
Pressure, 
Pounds. 

Initial 
Pressure, 
Pounds. 

Mean 
Effective 
Pressure. 
Pounds. 

Mean  Back   Pressure    includ- 
ing Compressions.     Pounds. 

I 

18 

10" 

158 

MS- 

98. 

9-5 

4 

24 

9" 

1  60 

MS. 

75- 

16. 

2 

29 

8" 

158 

143- 

66. 

17.5 

5 

33 

8" 

155 

138. 

58. 

18.5 

3 

42 

8" 

155 

137- 

52. 

24-5 

6 

54 

5" 

155 

130. 

40. 

23- 

materially.  The  difference  was  enough  to  make  quite  a 
saving  in  fuel.  Such  a  change  as  this  in  back  pressure 
produces  the  effect  on  an  engine  that  is  known  to  loco- 
motive engineers  as  "smarter,"  that  is,  the  engine  has  a 
livelier  action. 


138  COMPOUND    LOCOMOTIVES. 

Fig.  49a  illustrates  how  the  mean  effective  pressure  is 
effected  by  an  increase  or  decrease  of  back  pressure.  The 
two  sets  of  cards  shown  are  those  numbered  5  in  Tables 
AA  and  BB.  The  space  between  the  cards  that  is  sec- 
tioned by  vertical  lines  shows  the  change  in  mean  effective 
pressure  brought  about  by  a  variation  in  the  back  pressure. 
It  is  evident  from  this  illustration  that  the  effect  of  an  in- 
crease or  decrease  of  back  pressure  extends  over  the  entire 


FIG.  49a. 
Effect  of  Back  Pressure  on  Mean  Effective  Pressure. 

length  of  the  indicator  card.  The  reason  of  this  is  that 
when  the  back  pressure  is  increased  or  decreased  the  pres- 
sure at  the  commencement  of  compression  is  correspond- 
ingly increased  or  decreased,  and  the  whole  compression 
curve  is  therefore  effected.  The  conclusion  from  an  exam- 
ination of  Figs.  48,  49  and  4ga  must  be  that  a  careful  selec- 
tion of  exhaust  and  draught  apparatus  is  necessary  in  order 
to  produce  an  economical  and  powerful  engine  at  high 
speed. 


CHAPTER  XIV. 

EFFECT  OF  HEAVY  RECIPROCATING  PARTS. 

84  Weight  of  Reciprocating  Parts. —  It  is  of  the 
utmost  importance  that  the  weight  of  the  pistons,  cross- 
heads,  piston  rods,  main  rods,  and  in  fact  all  the  reciprocat- 
ing parts  of  a  locomotive  be  kept  down  to  the  lowest  limit. 
The  reason  is  that  these  parts  have  to  be  balanced  to  make 
the  engine  ride  steadily,  and  this  balance  acts  at  all  points 
of  a  revolution  of  the  drivers.  It  has  an  outward  or 
centrifugal  tendency  from  the  centre  of  the  .wheel  that  is 
very  great  at  high  speed.  This  tendency  of  that  part  of  the 
balance  that  is  used  for  the  reciprocating  parts  is  counter- 
acted only  when  the  balance  is  in  the  horizontal  position, 
that  is,  when  the  crank  is  at  the  end  of  the  stroke.  At 
other  times  the  centrifugal  tendency  is  upward  or  down- 
ward, and  is  unresisted  except  by  the  rail  or  the  springs 
above  the  axle  boxes.  This  centrifugal  tendency  is  some- 
times so  great  as  to  lift  the  wheel  from  the  rail.  And  it 
has  in  some  cases  seriously  damaged  the  tracks  during  a 
single  run  by  a  badly  balanced  locomotive  at  high  speed. 
It  is  then  necessary  to  reduce  the  weight  of  the  recipro- 
cating parts,  and  thereby  the  reciprocating  balance  as  much 
as  possible.  Unfortunately  compound  locomotives  carry 
with  them  a  necessity  for  larger  pistons.  These  large 
pistons  will  of  course  be  heavier  than  smaller  ones,  but  are 
not  necessarily  heavier  than  those  that  are  now  commonly 
used  here  for  single  expansion  engines.  In  the  United 
States  builders  are  much  behind  European  practice  in 
piston  and  crosshead  construction.  The  weight  of  the 
reciprocating  parts  used  here  is  more  than  twice  as  great 

139 


I4O  COMPOUND    LOCOMOTIVES. 

as  those  used  in  Europe  for  the  same  size  of  cylinder.  This 
results  from  the  use  here  of  a  cheaper  type  of  piston.  The 
foreign  type  is  generally  of  forged  steel  with  a  single  plate. 
Here  they  are  generally  made  of  cast  iron  with  double 
plates.  By  using  some  of  the  higher  grades  of  manganese 
steel,  or  aluminum  bronze,  or  by  using  forged  steel,  the  recip- 
rocating parts  of  either  a  two-cylinder  receiver  compound  or 
a  four  cylinder  non-receiver  compound  would  not  weigh 
more  than  the  reciprocating  parts  of  some  of  our  present 
single  expansion  engines. 

A  commendable  step  that  has  been  taken  in  the  reduction 
of  reciprocating  parts  is  the  removal  of  the  non-useful  weight 
in  the  Vauclain  crosshead  by  the  Baldwin  Locomotive 
Works.  This  is  shown  in  Fig.  119.  This  crosshead  is 
made  of  cast  steel  and  cored  out  to  remove  all  weight 
possible.  Such  reduction  of  weight  is  possible  in  all 
American  types  of  crossheads,  and  a  similar  reduction  is 
possible  with  American  pistons.  By  devoting  as  much 
attention  to  reduction  of  weights  and  reciprocating  parts  as 
the  matter  deserves,  the  total  weight  might  be  reduced  at 
least  50  per  cent. 

85.  Advantage  of  Large  Drivers. —  Large  drivers 
reduce  the  number  of  revolutions  per  minute,  and  thereby 
decrease  not  only  the  piston  speed,  but  also  the  effect  of 
the  counterbalance  weight,  and  therefore  a  large  wheel  is 
advantageous  for  a  compound,  as  it  reduces  the  wire-draw- 
ing and  compression  in  the  cylinders,  and  decreases  the 
effect  of  reciprocating  parts.  See  Fig.  50. 

•86.  Counterbalancing  of  Reciprocating  Parts.— 
Counterbalancing  is  a  matter  that  requires  especial  attention 
in  selecting  a  compound.  Only  the  lightest  practical  re- 
ciprocating parts  should  be  used,  and  the  practice  followed 
in  high  speed  marine  work  will  serve  as  a  guide. 

87.  Marine  Practice  in  Counterbalancing. — There 
are  large  triple  expansion  marine  engines  running  at  piston 


EFFECT    OF    HEAVY    RECIPROCATING    PARTS. 


141 


speeds   of  over   800   feet   per   minute.      The   piston    speed 
attained  by  the  quadruple  expansion  engines  of  the  torpedo 


0000 


0000 


60000 


5000O 


40000 


30000 


20000 


10000 


20 


4O  6O  8O 

SPEED    IN    MILES    AN    HOUR. 


1OO 


FIG.  50. 

Diagram  Showing  Decrease  in  Pressure  on  Track  Due  to  Counterbalance 
Which  Follows  an  Increase  in  the  Diameter  of  Drivers. 

boat  "Gushing"  was  925  feet   per  minute  on  her  trial,  and 
the  speed  of  pistons  of  the   triple   expansion   engines   of  a 


142  COMPOUND    LOCOMOTIVES. 

recent  Turkish  torpedo  boat  is  given  as  936  feet  per  minute 
on  a  trial  trip.  If  these  speeds  are  practicable  with  triple 
and  quadruple  expansion  engines,  there  does  not  appear  to 
be  any  good  reason  for  doubting  the  practicability  of  speeds 
of  1,100,  or  even  1,4.00  feet,  with  compound  locomotives. 
There  is  undoubtedly  a  maximum  limit  to  piston  speed, 
and  it  is  lower  for  compound  engines  than  for  single  ex- 
pansion engines,  but  the  limit  is  sufficiently  high  to  be  com- 
paratively unimportant  to  the  designer  of  locomotives. 
The  principal  factor  which  limits  the  speed  is  the  weight 
of  the  reciprocating  parts.  In  an  engine  working  at  a 
speed  of  250  revolutions  per  minute,  the  reciprocating 
parts  must  be  started  from  a  state  of  rest  at  the  beginning 
of  each  stroke,  and  their  speed  accelerated  to  about  26 
feet  per  second  during  approximately  a  half  stroke,  which 
occupies  about  0.06  second.  A  very  full  and  complete 
discussion  of  this  subject  will  be  found  in  a  paper  by  Mr, 
D.  S.  Jacobus,  in  Vol.  XI.  of  the  Transactions  of  the  Ameri- 
can Society  of  Mechanical  Engineers.  See  Appendix  P. 

The  pressure  per  square  inch  of  piston,  for  a  locomotive 
having  a  cylinder  18^  inches  in  diameter  and  24  inches 
stroke,  required  to  overcome  the  inertia  of  the  reciprocat- 
ing parts  and  accelerate  them  at  250  revolutions  per 
minute,  varies  from  about  55  pounds  at  10  degrees  from 
the  dead  point  to  o  at  about  80  degrees.  The  work  stored 
in  the  reciprocating  parts  during  the  first  half  of  the  stroke 
is,  of  course,  transmitted  to  the  crank  pin  during  the  last 
half  of  the  stroke.  But  the  effective  pressure  on  the  crank 
pin  during  the  first  half  stroke  is  only  that  due  to  the  differ- 
ence between  the  apparent  pressure  as  shown  by  the  indi- 
cator card  and  that  necessary  to  accelerate  the  reciprocating 
parts.  It  is  evident  that  if  the  pressure  of  the  steam  on  the 
piston  is  just  equal  to  that  required  for  acceleration  at 
any  position  of  the  piston,  no  pressure  will  be  transmitted  to 
the  crank  pin  at  that  point  in  the  stroke,  and  that  if  these 


EFFECT    OF    HEAVY    RECIPROCATING    PARTS. 


143 


pressures  are  equal  during  the  period  of  acceleration,  all 
pressure  which  is  transmitted  to  the  crank  pin  during  the 
stroke  will  be  during  the  second  half  stroke. 

The  pressure  necessary  to  produce  acceleration  varies 
directly  as  the  weight  of  the  reciprocating  parts,  and  as  the 
square  of  the  speed  of  rotation.  The  possible  means  of 
reducing  this  pressure  are  therefore  to  make  the  reciprocat- 
ing parts  lighter,  or  the  driving  wheels  of  greater  diameter 


O  2O  4O  6O 

SPEED  IN  MILES  AN  HOUR. 

FIG.  51. 

Diagram  Showing  Difference  in  Counterbalance  Pressure  on  Track  in 
American  and  Foreign  Engines. 

so  as  to  reduce  the  speed  of  rotation.  How  much  the 
distribution  of  pressures  on  the  crank  pins  will  be  affected 
by  such  changes  is  a  question  which  must  be  solved  by  the 
designer  in  each  case,  and  it  is  a  factor  which  is  worth 
careful  consideration,  more  on  account  of  the  crank-pin 
pressures  than  on  account  of  the  limitations  of  speed.  A 
considerable  reduction  in  weight  is  effected  by  the  use  of 


144 


COMPOUND    LOCOMOTIVES. 


steel,  wherever  practicable,  for  the  reciprocating  parts,  and 
the  adoption  of  the  most  economical  shapes  for  connecting 
and  coupling  rods,  pistons  and  cross-heads. 

88.  Effect  of  Decreasing  Weight  of  Reciprocating 
Parts  and  Increasing  Diameter  of  Drivers.  —  Fig.  51 
gives  the  maximum  pressure  on  a  rigid  track  due  to  that 
portion  of  the  counterbalance  of  a  locomotive  that  is  used 
to  counteract  the  horizontal  effect  of  the  reciprocating  parts 
of  American  and  foreign  locomotives  of  the  same  size  of 
cylinder.  This  diagram  also  illustrates  the  reduction  of 
the  variations  of  pressure  of  driving  wheels  upon  the  track 


P  20 

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FIG.  52. 

Diagram  Showing  Distribution  of  Counterbalance  Pressure  over  Track 

and  the  Per  Cent,  of  Maximum  Centrifugal   Pressure  Which 

Occurs  at  Different  Points  of  a  Revolution. 

that  follows  an  increase  in  the  diameter  of  the  driving 
wheels  and  a  reduction  of  the  weight  of  the  reciprocating 
parts. 

Fig.  50  shows  the  advantage  of  a  large  wheel  in  reduc- 
ing the  centrifugal  tendency.  The  pressures  given  are 
all  calculated  for  an  engine  with  an  18  X  24  cylinder 

89.  Distribution  of  Centrifugal  Tendency  of  Counter- 
balance over  the  Track. — Fig,  52  shows  the  variation  in 
the  per  cent,  of  the  maximum  centrifugal  tendency  of 
counterbalance,  which  is  exerted  on  the  track  at  different 


EFFECT    OF    HEAVY    RECIPROCATING    PARTS.         145 

points  during  a  complete  revolution  of  the  driving  wheels 
when  the  track  is  rigid  and  does  not  deflect  under  the  load 
due  to  the  centrifugal  tendency.  It  also  shows  how  the 
maximum  track  pressure  is  distributed  over  several  ties,  and 
how  it  gradually  increases  and  decreases. 


CHAPTER    XV. 

DESCRIPTION  OF  TWO  -  CYLINDER  RECEIVER  COMPOUNDS 
WITH  AUTOMATIC  INTERCEPTING  VALVE  STARTING 
GEARS,  AND  WITHOUT  SEPARATE  EXHAUST  FOR  HIGH- 
PRESSURE  CYLINDER  AT  STARTING. 

The  inauguration  of  the  present  era  of  compound  loco- 
motives in  Europe  is  due  to  Mr.  Anatole  Mallet,  who 
designed  successful  two- cylinder  compound  locomotives 
for  the  Bayonne  &  Biarritz  Railroad  in  1876,  and  has  since 
brought  out  many  different  designs.  While  it  would  not  be 
incorrect  to  class  the  greater  number  of  compound  locomo- 
tives as  belonging  to  the  Mallet  system,  this  term  as  applied  to 
two-cylinder  engines  is  usually  restricted  to  those  which  can 
be  operated  either  as  single  expansion  or  compound  engines 
at  the  will  of  the  engineer  (non-automatic)  as  distinguished 
from  those  which  are  necessarily  worked  as  compound 
engines,  except  for  a  brief  interval  in  starting  (automatic). 

The  disposition  of  cylinders  and  steam  chests  with 
regard  to  the  boiler  and  running  gear  of  two-cylinder  com- 
pound locomotives  does  not  differ  from  the  practice  in 
single  expansion  locomotives.  The  same  diversity  of  de- 
sign that  has  heretofore  been  remarkable  in  European 
practice  as  compared  with  the  American,  is  found  in  com- 
pound locomotives.  The  designer  will  find  precedent  in 
existing  engines  for  almost  any  arrangement  of  principal 
parts  and  for  any  type  of  valve  gear  which  he  is  likely  to 
adopt. 

There  have  been  quite  a  large  number  of  inventions  of 
somewhat  minor  value  in  the  details  of  starting  gear,  more 
particularly  of  the  automatic  type,  for  two-cylinder  com- 
pound locomotives,  and  a  number  of  patents  have  been  taken 

146 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  147 

out  in  this  and  foreign  countries,  but  as  a  rule  they  differ 
so  little  from  the  original  designs  of  Mallet  and  von  Borries 
that  the  patents  are  weak  and  the  scope  limited  to  some 
specific  construction.  It  is  impossible  to  give  within  the 
limits  of  these  pages  anything  like  a  complete  resume  of 
the  art  at  this  time  as  exhibited  in  the  Patent  Office.  It  is 
not  useful  to  do  so,  as  the  reader  would  be  confronted  with 
a  mass  of  drawings  and  descriptions  which  would  lead  to 
no  conclusions.  Only  the  principal  designs  and  such  as 
have  actually  been  put  into  service  are  here  described. 

90.  The  von  Borries  System  in  1889. — This  system 
is  strictly  automatic,  which  means  that  the  change  from  the 
use  of  boiler  steam  in  the  1.  p.  cylinder  to  full  compound 
action  is  made  automatically  without  the  will  of  the  engineer, 
and  takes  place  whenever  the  accumulated  pressure  of  the 
exhaust  from  the  h.  p.  cylinder  in  the  receiver  is  sufficient 
to  operate  the  automatic  mechanism.  Figs.  53  and  54  illus- 
trate one  of  the  arrangements  of  cylinders  and  steam  con- 
nections in  two  designs  of  compound  locomotives  according 
to  the  von  Borries  system.  In  both  figures  h  is  the  h.  p. 
cylinder,  /  is  the  1.  p.  cylinder,  A  is  the  steam  pipe  from  the 
boiler  to  the  h.  p.  cylinder,  C  is  the  receiver  connecting  the 
two  cylinders,  V  is  the  starting  and  intercepting  valve,  B  is 
the  auxiliary  steam  pipe  from  the  boiler  to  the  starting 
valve,  and  D  is  the  exhaust  pipe  from  the  1.  p.  cylinder. 

The  essential  feature  of  the  von  Borries  system  is  the 
combined  intercepting  and  starting  valve,  an  early  form  of 
which  is  illustrated  by  Fig.  55.  In  this  figure  a  is  the 
receiver  pipe  which  leads  from  the  h.  p.  cylinder  and  b  is 
the  passage  to  the  1.  p.  cylinder.  The  valve  is  shown  in  the 
position  which  it  occupies  ordinarily,  or  when  the  locomo- 
tive is  working  as  a  compound  engine,  the  direction  of  the 
flow  of  the  steam  being  as  indicated  by  the  arrows.  Con- 
nected to  the  back  of  the  intercepting  valve  v  are  two  small 
plungers  c  c  which  together  form  the  starting  valve.  Sup- 


148 


COMPOUND    LOCOMOTIVES. 


FIG.  53 


FIG.  54. 

Arrangement  of  Cylinders  and  Intercepting  Valve  with  von  Borries 
Automatic  Starting  Gear. 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


49 


posing  the  valves  to  be  in  the  positions  shown  in  Fig.  55 
and  the  engine  about  to  start,  when  the  throttle  is  opened 
steam  will  be  admitted  to  the  h.  p.  cylinder  by  the  usual 
pipe,  and  also  to  the  auxiliary  steam  pipe  d,  and  by  the 
passage  shown  to  the  back  of  the  plungers.  The  pressure 
on  the  ends  of  the  plungers  is  sufficient  to  move  the  inter- 
cepting valve  v  to  the  left  in  the  figure  until  it  seats  at  e. 
By  the  same  movement  two  small  ports  h  h  are  uncovered, 
through  which  steam  from  the  boiler  is  admitted  to  the 
passage  b  and  thence  direct  to  the  1.  p.  steam  chest,  while, 
as  the  intercepting  valve  is  closed,  this  pressure  does  not 
act  against  the  h.  p.  piston. 


FIG.  55. 
von  Borries  Intercepting  Valve,  Early  Form. 

As  the  engine  starts  and  the  exhaust  from  the  h.  p. 
cylinder  takes  place,  the  pressure  in  the  receiver  rises  until 
it  is  sufficient  to  overcome  the  pressure  on  the  1.  p.  side  of 
the  intercepting  valve,  when  this  valve  is  moved  back  to 
the  position  shown  in  the  figure,  while  at  the  same  time  the 
two  small  steam  ports  are  closed  by  the  plungers,  and  the 
engine  begins  to  work  as  a  compound.  It  is  said  that  in 
practice  the  pressure  of  the  steam  from  the  boiler  which  is 
admitted  to  the  1.  p.  cylinder  is  reduced  by  wire-drawing, 
due  to  the  small  steam  pipe  and  ports,  to  about  one-half  the 
boiler  pressure,  and  as  the  ratio  of  the  cylinders  is  about 


150 


COMPOUND    LOCOMOTIVES. 


2,  the  total  pressure  on  the  two  pistons  in  starting  is 
nearly  equal.  To  prevent  excessive  pressure  in  the  1.  p. 
cylinder  and  receiver  a  safety  valve  is  placed  on  the  latter. 
The  pressure  in  the  receiver  when  running  is  sufficient 
to  overcome  the  boiler  pressure  acting  on  the  ends  of  the 
two  small  plungers,  together  with  the  atmospheric  pressure 
on  the  stem  of  the  large  valve  v,  and  therefore  the  valves 
are  maintained  in  the  position  shown  in  Fig.  55  as  long  as 
the  engine  is  running  under  steam. 


FIG.  56.  FIG.  57. 

von  Borries  Intercepting  Valve  as  Used  on  Jura,  Berne-Lucerne  Ry. 

91.  The  von  Borries  System,  as  used  on  the  Jura, 
Berne-Lucerne  Railway. — To  facilitate  starting,  the  engine 
is  fitted  with  a  von  Borries  automatic  starting  valve,  the 
construction  of  which  is  shown  by  the  detail  views,  Figs. 
56  and  57,  annexed.  This  apparatus  is  placed  at  the 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  151 

junction  of  the  intermediate  receiver  or  connecting  pipe 
with  the  1.  p.,  the  steam  leaving  this  intermediate  receiver 
at  R  and  passing  off  to  the  1.  p.  cylinder  at  C.  If  the  engine 
stops  with  the  h.  p.  piston  on  a  dead  point,  so  that  the 
engine  cannot  start  in  the  ordinary  way  and  no  steam  can 
be  exhausted  to  the  1.  p.  cylinder,  the  live  steam  passes 
from  the  h.  p.  valve  chest  through  the  pipe  /  and  acts  upon 
the  lower  end  of  the  spindle  K,  the  pressure  thus  exerted 
raising  the  valve  5  and  closing  it  on  the  seat  Si.  When  the 
spindle  K  is  thus  lifted  it  uncovers  the  small  openings  e  e, 
and  live  steam  can  then  pass  to  the  1.  p.  cylinder,  thus 
starting  the  engine.  As  soon  as  the  engine  gets  to  work 
the  exhaust  from  the  h.  p.  cylinder,  of  course,  raises  the 
pressure  in  the  intermediate  receiver,  and  this  pressure 
acting  on  the  valve  5  overpowers  the  pressure  of  the  live 
steam  on  the  lower  end  of  the  spindle  K  and  the  receiver 
pressure  on  the  valve  S,  and  forces  the  valve  off  its  seat, 
thus  allowing  the  exhaust  steam  from  the  h.  p.  cylinder  to 
pass  to  the  1.  p.,  the  engine  then  continuing  to  work  com- 
pound. To  insure  the  valve  S  being  forced  down  into  the 
position  in  which  it  is  shown  in  Figs.  56  and  57,  there  is 
provided  a  small  piston  p  working  in  a  cylinder  a}  the 
upper  end  of  which  is  in  free  communication  with  the 
receiver.  The  area  of  this  piston  is  such  that  the  pressure 
of  the  receiver  steam  on  it  is  sufficient  to  over-power  the 
pressure  of  the  live  steam  on  the  lower  end  of  the  spindle  K. 
92.  A  Modification  of  the  von  Borries  System. — A 
modification  of  the  von  Borries  intercepting  valve  is  shown 
in  Fig.  58.  This  valve  is  placed  in  the  side  of  the 
smoke  box,  and  is  connected  at  A  by  a  small  pipe  to  the 
steam  pipe  from  the  boiler.  When  the  throttle  is  opened 
steam  enters  the  passage  C  by  way  of  the  pipe,  and  press- 
ing against  the  shoulder  of  the  steel  spindle  D,  pushes  it 
into  the  position  shown  in  Fig.  58,  and  thus  closes  the 
valve.  The  steam  then  passes  around  the  spindle,  out 


152 


COMPOUND    LOCOMOTIVES. 


through  the  y2  inch  opening  and  into  the  chamber  B,  which 
communicates  with  the  receiver.  Then  it  has  free  access 
to  the  steam  chest  of  the  1.  p.  cylinder.  It  also  acts  against 
the  piston  E  through  the  passage  F,  but  the  greater  area  of 
the  main  valve  keeps  it  closed. 


FIG.  58. 
Recent  Modification  of  von  Borries  Intercepting  Valve. 

When  the  h.  p.  cylinder  exhausts  into  the  chamber  A, 
the  pressure,  which  has  heretofore  been  equal  to  that  of  the 
atmosphere,  rises  on  that  side  of  the  valve  and  thus  balances 
the  receiver  pressure.  Then,  as  the  area  of  E  is  greater 
than  that  of  the  shoulder  on  D  the  valve  is  moved  to  the 
right,  and  the  communication  between  the  h.  p.  exhaust 
and  the  receiver  is  again  established.  In  this  position  the 
larger  portion  of  the  stem  D  closes  the  ^  inch  openings  and 
the  engine  works  as  a  compound.  It  may  be  added  that  the 
openings  are  so  graded  that  the  steam  is  wire-drawn  down 
to  the  proper  pressure  for  admission  to  the  1.  p.  cylinder. 


TWO-CYLINDER    RECEIVER    COMPOUNDS, 


153 


93.  Recent  Changes  in  the    von  Borries   System.— 

After  several  years  careful  watching  of  the  locomotives 
fitted  with  automatic  intercepting  valves,  Mr.  von  Borries 
has  reached  the  conclusion  that  it  is  better  to  give  to  the 
engineer  a  control  over  the  intercepting  valve,  and  to  pro- 
vide a  separate  exhaust  for  the  h.  p.  cylinder  at  starting. 
With  this  change  in  view  a  new  arrangement  of  starting 
gear  has  been  devised.  It  is  described,  with  other  non- 
automatic  starting  gears,  in  Chapter  XVII,  116. 

94.  The  Worsdell    System, — This  system  is  strictly 
automatic,  which   means  that  the   change  from  the  use  of 
boiler  steam  in  the  1.  p.  cylinder  to  full  compound  action  is 


FIG.  59. 
Arrangement  of  Cylinders,  Worsdell  Two-Cylinder  Type. 

controlled  automatically  beyond  the  will  of  the  engineer, 
and  takes  place  whenever  the  pressure  in  the  receiver, 
resulting  from  the  exhaust  of  the  h.  p.  cylinder,  rises  to  a 


154 


COMPOUND    LOCOMOTIVES. 


point  .where  it  is  sufficient  to  actuate  the  automatic 
mechanism.  In  Fig.  59  h  and  /  represent  the  h.  p.  and 
1.  p.  cylinders,  respectively,  A  is  the  h.  p.  steam  pipe,  C  is 
the  receiver,  D  is  the  1.  p.  exhaust  pipe,  B  is  the  steam 


FIG.  61. 

Early  Form  of  Worsdell  Intercepting  Valve. 

• 

supply  to   the   starting  valve   v}  and    V  is  the  intercepting 
valve. 

The  Worsdell  starting  and  intercepting  valves  are  illus- 
trated by  Figs.  60  and  61.  The  intercepting  valve  is  a  flap 
valve,  and  is  shown  in  Fig.  60  in  the  position  which  it 
occupies  when  the  engine  is  working  as  a  compound,  being 
swung  to  one  side,  and  thus  leaving  a  straight,  clear  passage 
by  it.  The  spindle  on  which  the  valve  turns  passes  out 
through  the  side  of  the  smoke  box,  and  carries  an  arm, 


,     TWO-CYLINDER    RECEIVER    COMPOUNDS.  155 

which  is  connected  to  the  small  piston  shown  at  a,  Fig.  61, 
in  a  manner  which  is  clearly  indicated  in  the  figures.  The 
starting  valve  casing  is  connected  to  the  main  steam  pipe 
by  a  small  pipe,  which  is  shown  in  Fig.  61,  and  also  in  Fig. 
59.  The  piston  a,  which  operates  the  intercepting  valve  by 
means  of  the  connection  previously  referred  to,  works  in  a 
cylinder  which  is  an  extension  of  the  starting  valve  casing. 

A  small  port,  which  is  covered  by  a  spring-loaded  valve, 
connects  this  cylinder  with  the  pipe  6,  and  thus  to  the 
intercepting  valve  chamber.  The  starting  valve  is  operated 
by  a  lever,  and  is  a  double  valve,'  a  slight  movement  of  the 
lever  opening  the  smaller  valve,  and  further  motion  opening 
the  larger  valve,  which  is  then  partially  balanced. 

The  operation  of  these  valves  in  starting  is  as  follows: 
The  starting  valve  being  opened  by  the  engineer,  steam,  at 
boiler  pressure,  acts  upon  the  small  piston  a,  and  moves  it 
forward  or  to  the  left  in  the  Fig.  61.  By  the  same  movement 
the  intercepting  valve  is  swung  up  and  closed,  and  the  port 
connecting  with  the  pipe  b  is  uncovered,  thus  admitting 
steam  from  the  boiler  to  the  intercepting  valve  chamber 
below  the  valve,  and  thence  to  the  1.  p.  steam  chest.  As 
the  exhaust  takes  place  from  the  h.  p.  cylinder,  the  pressure 
in  the  receiver,  above  the  intercepting  valve,  rises  until  it  is 
sufficient  to  open  that  valve,  when,  by  its  movement,  the 
small  piston  a  is  returned  to  the  position  shown  in  Fig.  6.1, 
and  the  steam  supply  is  thus  shut  off. 

95.  A  Modification  of  the  Worsdell  System.  —  This 
is  shown  in  Figs.  62  and  63.  It  is  automatic  in  action,  as  it 
allows  live  steam  to  be  admitted  to  the  1.  p.  cylinder  at  start- 
ing and  automatically  cuts  off  this  supply,  thus  converting 
the  engine  into  a  compound  when  the  receiver  pressure 
has  been  raised  to  the  proper  point  by  the  h.  p.  exhaust. 

When  the  engine  driver  opens  the  throttle  valve,- steam 
is  admitted  through  the  holes  A  A  over  the  stems  of  the 
plungers  C  C.  These  plungers  are  then  forced  to  the  right, 


156 


COMPOUND    LOCOMOTIVES. 


pushing  the  main  valve  against  its  seat  and  opening  the 
port  holes  B  B  that  connect  with  the  chamber  E,  as  shown 
in  the  cross  section,  Fig.  63,  which  leads  directly  to  the 
steam-chest  of  the  1.  p.  cylinder.  Thus  the  live  steam  is 


FIG.  62. 
Recent  Modification  of  Worsdell  Intercepting  Valve. 

also  admitted  below  the  relief  valve  //,  so  that  should  the 
pressure  in  the  1.  p.  steam-chest  rise  above  that  desired,  this 
valve  will  open  and  allow  the  excess  of  steam  to  escape  into 
the  smoke-box.  The  small  flap  valve  G  which  closes  the 
passage  F  from  the  safety  valve  is  used  to  prevent  an 
accumulation  of  cinders  collecting  about  the  safety  valve  as 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


157 


a  result  of  long  disuse.  A  drop  pipe  K  is  also  provided  to 
carry  off  the  water  condensation  and  leakage  from  the 
annular  space  0. 

After  the  h.  p.  cylinder  has  exhausted  into  the  chamber 
D,  the  pressure   in  that   chamber  rises    so  that  finally    the 


FIG.  63. 
Modification  of  Worsdell  Intercepting  Valve. 

pressure  on  the  under  side  of  the  valve  overcomes  that  on 
the  stems  C  C,  and  the  valve  opens,  re-establishing  com- 
munication between  the  exhaust  D  of  the  h.  p.  cylinder  and 
the  receiver  E  of  the  1.  p.  At  the  same  time  the  stems  C  C 
close  the  ports  B  B  and  the  engine  proceeds  with  its  work 
as  a  compound.  The  plug  shown  screwed  into  the  valve 
is  merely  used  to  plug  up  the  core  hole  made  in  casting  the 
valve. 

96.  The  Schenectady  Locomotive  Works  (Pitkin) 
System. — This  system  is  strictly  automatic,  inasmuch  as  the 
change  from  the  use  of  steam  directly  from  the  boiler  into 
the  1.  p.  cylinder  is  controlled  automatically  and  is  beyond 
the  will  of  the  engineer.  The  change  from  the  use  of  steam 
directly  in  the  1.  p.  cylinder  to  full  automatic  action  occurs 
whenever  the  exhaust  pressure  from  the  h.  p.  cylinder  accum- 
ulates in  the  receiver  to  a  point  where  it  will  actuate  the  auto- 


158 


COMPOUND    LOCOMOTIVES. 


matic  mechanism.  The  general  arrangement  of  the  cylinders 
and  steam  connections  of  this  locomotive  is  show  by  Fig. 
64.  The  distinctive  feature  of  the  engine  is  the  intercept- 
ing valve,  which  is  shown  by  Fig.  65,  which  is  a  plan  of  the 
bushing  which  incloses  the  valve,  and  by  Fig.  66  which  is  a 
vertical  section  through  the  valve,  bushing  and  saddle. 

The  valve  is  shown  in  the  position  which  it  occupies  in 
starting;  that  is,  before  compound  working  begins.      In  this 


FIG.  64. 
Arrangement  of  Cylinders  and   Receiver,  Schenectady  (Pitkin)  Type. 

position  the  ports  c  and  d  are  closed  oy  the  intercepting 
valve  and  the  connection  between  the  1.  p.  steam  chest  and 
the  receiver  is  thus  cut  off.  The  small  port  a,  Fig.  65,  is 
connected  by  a  pipe  and  a  pressure-reducing  valve  to  the 
h.  p.  steam  pipe.  By  this  means  steam  at  reduced  pressure 
is  admitted  to  the  space  b  and  thence,  as  indicated  by  the 
arrow,  to  the  1.  p.  steam  chest.  As  the  parts  of  the  valve 
on  either  side  of  b  are  of  different  diameters,  the  pressure 
in  this  space  tends  to  hold  the  valve  in  the  position  shown 
in  Fig.  66.  When  the  locomotive  starts,  the  h.  p.  cylinder 
exhausts  into  the  closed  receiver,  and  the  back  pressure 
thus  created  acts  upon  the  forward  end  of  the  intercepting 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


159 


valve  by  means  of  the  passage  shown  at  e.     The  pressure  in 
the  receiver  rapidly  increases  until  the  total  pressure  on  the 


forward  end  of  the  valve  is  sufficient  to  overcome  the  total 
effective  pressure  at  b,  when  the  valve  is  forced  to  the  back 
end  of.  its  stroke,  the  direct  steam  supply  to  the  1.  p.  cyl- 


l6o  COMPOUND    LOCOMOTIVES. 

inder  is  cut  off,  and  compound  working  begins.  To  prevent 
the  valve  moving  too  rapidly  a  dash-pot,  in  the  form  of  an 
oil  cylinder,  h,  is  added.  The  valve  stem  is  continued 
through  this  oil  cylinder,  and  is  connected  by  levers  to 
an  index  in  the  cab  which  indicates  the  position  of  the 
valve. 

97.  A  Modification  of  the  Schenectady  Locomotive 
Works  (Pitkin)  System. — This  system  is  illustrated  by 
Figs.  67  to  71  inclusive.  There  are  two  pistons  A  A  at 
one  end  of  the  single  stem  B,  which  moves  to  and  fro  in  a 
cylindrical  chamber  having  three  openings.  Two  of  these 
openings,  C  C,  lead  to  the  receiver  and  to  the  1.  p.  steam 
chest,  and  it  is  the  office  of  the  pistons  A  A  to  open  and 
close  these  large  openings  and  prevent  the  steam  in  the  1. 
p.  steam  chest  from  entering  the  receiver  when  it  is  not 
wanted  there.  The  other  opening,  D,  in  this  cylinder, 
connects  the  intercepting  valve  cylinder  with  the  1.  p.  steam 
chest.  There  are  holes  through  the  pistons  A  A  which 
admit  the  1.  p.  steam  chest  pressure  to  the  right  hand  end 
and  thus  balance  these  pistons  and  prevent  movement  by 
either  receiver  pressure  or  by  the  pressure  in  the  1.  p. 
.steam  chest. 

The  remaining  portion  of  the  mechanism  is  the  appa- 
ratus for  driving  and  connecting  the  intercepting  valve.  It 
is  constructed  as  follows : 

On  the  end  of  the  stem  B,  which  passes  through  a  stuff- 
ing box  in  the  end  of  the  intercepting  valve  chamber,  there 
is  a  piston  E,  which  moves  in  a  small  cylinder  having  ports 
F  and  G,  one  at  each  end.  These  ports  lead  to  a  valve  seat 
on  which  is  a  plain  D  valve  not  unlike  the  ordinary  locomo- 
tive* slide  valve.  This  slide  valve  is  moved  to  and  fro  by 
means  of  a  double  piston  with  a  stem  between,  shown  at 
/and  K.  These  pistons  are  of  different  diameters,  A' being 
larger  than/;  and  as  they  move  to  and  fro. they  carry  with 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  l6l 


FIG.  67. 

Modification  of  the  Schenectady  Automatic  Intercepting  Valve. 
Complete  Details. 


FIG.  68. 

Modification  of  the  Schenectady  Automatic   Intercepting  Valve. 
Plan  Intercepting  Valve  Open. 


l62  COMPOUND    LOCOMOTIVES. 

them  the  slide  valve.  The  office  of  this  portion  of  the 
mechanism  is  to  move  the  intercepting  valve  A  A  to  and 
fro  as  desired. 

The  third  part  of  the  device  consists  of  a  balance  poppet 
valve  L,  which  is  placed  in  the  path  of  steam  coming  direct 
from  the  boiler  to  the  1.  p.  cylinder  to  assist  in  starting. 
This  valve  has  an  extended  spindle,  M,  on  the  lower  side, 
and  is  lifted  by  means  of  a  bell  crank,  N,  which  is  driven  by 
means  of  a  trunnion  on  the  intercepting  valve  stem  B.  As 
the  stem  B  passes  to  the  right,  the  valve  L  is  lifted,  and  as 


FIG.  69.  FIG.  70. 

Details  of  Modification  of  Schenectady  Automatic  Intercepting  Valve. 

it  passes  to  the  left  the  valve  L  is  allowed  to  fall.  Fig.  69 
is  a  detail  of  the  pipe  connections  and  passages  leading  to 
the  pistons  JK,  the  office  of  which  will  be  described  in  what 
follows.  Fig.  70  is  a  section  through  the  slide  valve  H 
showing  that  it  has  a  cylindrical  seat.  The  operation  of  this 
valve  is  a  follows: 

The  engineer  opens  the  throttle,  as  usual.  Boiler  steam 
passes  through  the  pipe  P,  which  is  tapped  into  the  h.  p. 
steam  pipe  to  the  apparatus  which  actuates  the  intercepting 
valve,  as  shown  in  Figs.  68  and  69.  It  enters  through  Q 
and  forces  the  small  regulating  valve  R  to  the  right  and 
then  passes  down  through  the  left  port  5  between  the  pistons 
J  and  K.  K  being  larger  than  /,  it  has  a  greater  total 
pressure  ;  hence,  the  pistons  move  to  the  right  and  carry  the 
slide  valve  with  them.  This  opens  the  port  F  and  allows 
the  steam  to  pass  on  the  left  side  of  the  piston  E,  and  forces 
it,  together  with  the  intercepting  valve  A  A,  to  the  right 
until  it  is  in  the  position  shown  in  Fig.  71,  with  the  C  C 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


163 


passages    closed.     The  position  of  the  pistons  /  K  and  the 
slide  valve  //at  this  time  are  shown  in  Fig,  71. 

During  the  foregoing  operation,  as  the  intercepting  valve 
stem  B  moves  to  the  right  it  carries  with  it  the  bell  crank  N 
to  the  position  shown  in  Fig.  71,  thus  lifting  the  balance 
poppet  valve  L  and  admitting  steam,  as  shown  by  the  arrows, 
Fig.  71,  into  the  intercepting  valve  cylinder,  from  whence 


FIG.  71. 

Modification  of  Schenectady  Automatic  Intercepting  Valve. 
Intercepting  Valve  Shut. 

it  passes  out  through  the  opening  D  into  the  1.  p.  cylinder 
steam  chest,  and  in  this  way  steam  is  admitted  direct  from 
the  boiler  to  the  1.  p.  steam  chest  always  just  before  the 
engine  starts. 

As  soon  as  the  engine  has  started  and  there  is  an  exhaust 
into  the  receiver  from  the  h.  p.  cylinder,  steam  passes  from 
the  receiver  through  the  pipe  T,  shown  in  Fig.  69,  to  the 
passages  U leading  to. the  piston  K.  This  pressure  acts  on 
the  right  hand  side  of  the  regulating  valve  R,  moves  it  to  the 
left  thus  opening  the  right  port  5  and  also  acting  on  the 
larger  piston  K,  moves  the  slide  valve  H  and  opens  the 
steam  passage  G,  Fig.  68,  and  the  exhaust  passage  V,  and 
admits  steam  to  the  right  hand  side  of  the  piston  E,  and 
drives  it  to  the  left,  and  with  it  the  intercepting  valves  A 
A,  thus  opening  the  passages  C  C  and  the  receiver  to  the  1. 
p.  steam  chest.  At  the  same  time  the  bell  crank  N  is 


164 


COMPOUND    LOCOMOTIVES. 


moved  to  the  left  and  the  valve  L  is  al  )\ved  to  drop  into 
the  position  shown  in  Fig.  68,  thus  cutting  off  the  connec- 
tion between  the  boiler  and  the  1.  p.  steam  chest.  After  this 
the  engine  works  in  the  well-known  way  of  the  two-cylinder 
compound ;  that  is,  by  taking  steam  into  the  h.  p.  cylinder, 


FIG. 
Location  of  Schenectady  Modified  Intercepting  Valve 

discharging  it  into  the  receiver,  taking  it  out  of  the  receiver 
into  the  1.  p.  cylinder  and  discharging  it  into  the  atmos- 
phere. Fig.  69  shows  the  external  appearance  of  the 
mechanism. 

One  of  the  Schenectady  two-cylinder  compounds  on  the 
Southern  Pacific  has  been  fitted  with  an  independent  exhaust 
for  the  h.  p.  cylinder.  The  arrangement  is  simply  a  piston 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  165 

valve  attached  to  a  receiver  pipe  that  is  actuated  from  the 
cab.  At  starting,  or  whenever  it  is  desirable  to  run  the 
engine  with  a  separate  exhaust  for  the  h.  p.  cylinder,  the 
engineer  moves  a  handle  in  the  cab  which  opens  the  piston 
valve  to  the  atmosphere. 

98.  The  Dean  System.— This  system  is  strictly  auto- 
matic, inasmuch  as  the  change  from  the  use  of  steam  directly 
from  the  boiler  into  the  1.  p.  cylinder  is  controlled  automa- 
tically, and  is  beyond  the  will  of  the  engineer.     The  change 
from   the   use   of   steam  directly  in  the  1.  p.  cylinder  to  full 
automatic  action  occnrs  whenever  the  exhaust  pressure  from 
the  h.  p.  cylinder  accumulates  in  the   receiver  to   a    point 
where    it    will  actuate  the  automatic    mechanism.     In   the 
first  design  the  intercepting  valve  operated  almost  exactly 
as   that  now  used,  but  it  was    located    in  the  smoke  box. 
The  converting  valve  was  placed  on  the  h.  p.  steam  chest 
cover   as    shown    in    Fig.    74.      In  the    present  design  the 
intercepting  valve  and  converting  valve  are  joined  together 
and   are   located   on  the  h.  p.  steam  chest.     The  receivers 
are  made  of  cast  iron  with  ribs,  as  shown  in  Fig.  72. 

99.  A  Modification  of  the  Dean  System.  —  Recently 
this  gear  has  been  modified,  and  the  intercepting  and  con- 
verting valves  are  bolted  to  the  top  of  the  h.  p.  steam  chest 
cover,  and  have  connected  to  them  a  ^  -inch  steam  pipe  for 
conveying  live  steam  to  the  intercepting  valve  for  lifting  it 
and  securing  it  in  its  highest  position.     See  Fig.  72.     This 
pressure  is    from   the    boiler    and    is  exerted  at    all  times 
whether  the  engine  is  running  or  not. 

The  h.  p.  main  slide  valve  is  open  at  the  top,  and  the 
exhaust  steam  from  the  h.  p.  cylinder  passes  upward  through 
it  and  a  port  in  the  balance  plate  into  the  steam  chest  cover, 
instead  of  down  through  a  port  in  the  cylinder  as  usual  ;  by  a 
passage  shown  in  Figs.  72  and  75  it  passes  to  the  receiver. 

The  starting  valves  consist  of  a  converting  valve  and  an 
intercepting  valve.  The  former  seats  over  a  hole  in  the 


1 66 


COMPOUND    LOCOMOTIVES. 


live  steam  part  of  the  steam  chest  cover,  see  Figs.  73  and 
74.  When  the  throttle  valve  opens  the  converting  valve  is 
lifted  and  steam  passes  through  into  the  intercepting  valve, 


FIG.  72. 

Dean's    Automatic    Intercepting     Valve — Cross    Section    Through    Cylinders, 
•         and  Plan  of  Steam  Chest. 

see  Fig.  73,  which  is  forced  down  slowly  on  account  of  the 
steam  being  wire-drawn  through  small  holes  in  the  inter- 
cepting valve,  and  because  of  the  boiler  steam  that  holds 
up  the  intercepting  valve,  see  Fig.  75.  When  the  inter- 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


I67 


cepting  valve  is  nearly  on  its  seat  radial  holes  in  the  valve 
allow  live  steam  from  the  converting  valve  to  pass  through 
into  the  receiver  and  into  the  1.  p.  cylinder.  Thus  the  1. 


FIG.  73- 

Dean's  Automatic  Intercepting  Valve — Longitudinal  Section 
Through  High-Pressure  Cylinder. 

p.  cylinder  receives  steam  for  starting.  When  the  h.  p. 
cylinder  exhausts,  the  pressure  in  the  receiver  acts  through 
a  passage,  shown  in  Fig.  74,  on  the  top  of  the  converting 
valve,  moves  it  downward,  and  shuts  off  the  supply  of  live 
steam.  At  the  same  time  the  grooved  stem  at  the  bottom 


1 68 


COMPOUND    LOCOMOTIVES. 


of  the  converting  valve  allows  the  steam  that  is  holding 
the  intercepting  valve  down  to  escape  into  the  atmosphere, 
and  thus  enables  the  boiler  steam  in  .the  annular  space 
around  the  intercepting  valve  to  lift  that  valve.  The 
engine  then  acts  as  a  compound  engine. 


FIG.  74. 

Dean's  Converting  Valve — Cross  Section  Through    High- 
Pressure  Cylinder,  before  Modification. 

In  order  to  prevent  the  steam,  coming  from  the  con- 
verting valve  at  starting,  from  getting  under  the  intercept- 
ing valve,  the  disc  of  that  valve  enters  a  lip  around  its  seat 
before  the  starting  steam  is  allowed  to  enter  the  receiver. 

Both  valves  are  cushioned  to  prevent  slamming  in  either 
direction,  and  provision  is  made  for  oiling. 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  169 


FIG.  75. 

Dean's  Modified   Automatic  Intercepting  Valve  —  Cross  Section  Through 
High-Pressure  Cylinder. 

100.  The  Brooks  Locomotive  Works  (Player) 
System. — This  system  is  strictly  automatic,  inasmuch  as 
the  change  from  the  use  of  steam  directly  from  the  boiler 
into  the  1.  p.  cylinder  is  controlled  automatically,  and  is 
beyond  the  will  of  the  engineer.  The  change  from  the  use 
of  steam  directly  in  the  1.  p.  cylinder  to  full  automatic 
action  takes  place  whenever  the  exhaust  pressure  from  the 
h.  p.  cylinder  accumulates  in  the  receiver  to  a  point  where 
it  will  actuate  the  automatic  mechanism.  It  is  shown  in 
Figs.  76,  77,  78,  78a. 


I7O  COMPOUND    LOCOMOTIVES. 

The  exhaust  from  the  h.  p.  cylinder  passes  into  the 
receiver  as  usual.  Its  passage  to  the  1.  p.  cylinder  is  gov- 
erned by  an  intercepting  valve,  shown  in  detail  in  Figs.  78 
and  78a.  A  pipe  leads  from  the  main  steam  pipe  to  the  end 
of  the  intercepting  valve,  as  shown  in  Figs.  76  and  77,  and  the 
steam  entering  there  when  the  throttle  is  opened  forces  the 
duplex  piston  forward  and  closes  the  intercepting  valve,  as 
shown  in  Fig.  78.  The  intercepting  valve  is  formed  of  an 
annular  piston  which  works  on  the  outside  of  the  duplex 
piston,  as  shown.  As  the  duplex  piston  moves  forward, 
steam  is  admitted  through  the  interior  of  that  piston,  see 
Fig.  78a,  and  into  the  receiver,  and  passes  thence  to  the  1.  p. 
cylinder.  In  this  way  the  pressure  in  the  receiver  increases 
and  finally  returns  the  duplex  piston  to  its  seat,  see  Fig.  78, 
and  stops  the  admission  of  boiler  steam  to  the  1.  p.  cylinder. 
This  last  movement  is  caused  by  the  pressure  in  the  receiver 
acting  on  the  larger  piston  of  the  duplex  piston,  against  the 
steam  pipe  pressure  acting  on  the  smaller  piston  of  the 
duplex  piston.  In  this  way  the  duplex  piston  becomes  a 
reducing  valve,  which  reduces  pressure  of  the  steam  between 
the  steam  pipe  and  the  1.  p.  cylinder  according  to  the  area 
of  the  two  pistons  of  the  duplex  piston.  When  the  pressure 
in  the  receiver  has  been  raised  by  the  exhaust  from  the  h.  p. 
cylinder,  the  intercepting  valve  is  forced  open  and  the 
admission  of  steam  from  the  steam  pipe  is  shut  off  by  the 
valve-end  of  the  duplex  piston  which  is  forced  back  to  its 
seat.  There  is  an  outlet  to  the  atmosphere  which  prevents 
the  pressure  accumulating  on  the  back  side  of  the  annular 
piston  of  the  intercepting  valve,  see  Figs.  78  and  78a. 

In  order  to  move  or  stop  the  engine  quickly  when 
desired,  as  for  round  house  work,  two  valves  are  attached 
to  the  receiver,  one  on  the  h.  p.  side  and  the  other  on  the  1. 
p.  side,  which  can  be  opened  by  a  lever  in  the  cab.  The 
opening  of  the  valve  on  the  h.  p.  side  permits  the  engine  to 
be  used  like  a  single  expansion  engine  in  a  very  limited  way, 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


171 


as  the  exhaust  from  the  h.  p.  is  allowed  to  pass  to  the 
atmosphere  through  this  comparatively  small  auxiliary  valve. 
The  valve  on  the  1.  p.  side  of  the  receiver  is  kept  shut  while 
the  engine  is  being  moved,  but  when  it  is  desired  to  stop 


quickly,  the  opening  of  this  valve  permits  the  escape  of  all 
the  steam  in  the  1.  p.  steam-chest  and  in  the  1.  p.  side  of  the 
receiver.  In  this  way  the  locomotive  is  stopped  quicker 
than  it  would  be  if  the  cylinders  had  been  used  compound. 
101.  Rogers  Locomotive  Works  System. —  This 
system  is  strictly  automatic,  inasmuch  as  the  change 


172 


COMPOUND    LOCOMOTIVES. 


from  the  use  of  steam  directly  from  the  boiler  into  the  1.  p, 
cylinder  is  controlled  automatically  and  is  beyond  the  will 


FIG.  77. 

Brooks  (Player)  Automatic  Intercepting  Valve  —  Longitudinal  Section 
Through  Low-Pressure   Cylinder. 

of  the  engineer.     The  change  from  the  use  of  steam  directly 
from  the  1.  p.  cylinder  to  full  automatic  action  takes  place 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  173 

whenever  the  exhaust  pressure  from  the  h.  p.  cylinder  accu- 


FIG.  78. 
Brooks  (Player)  Automatic  Intercepting  Valve  —  Reducing  Valve  Closed. 


FIG.  78a. 
Detail  of  Brooks  Automatic  Intercepting  Valve — Reducing  Valve  Open. 

mulates  in  the  receiver  to  a  point  where  it  will  actuate  the 
automatic  mechanism.      It  is  shown  in  Figs.  79,  80  and  81. 


174 


COMPOUND    LOCOMOTIVES. 


The  intercepting  and  reducing  valves  are  shown  in  detail 
in  Fig.  79.  The  reducing  valve  consists  of  a  valve  B  and 
piston  A,  mounted  on  a  stem  F,  in  an  iron  chamber/,  the 
space  between  the  valve  and  piston  being  filled  by  steam 
supplied  from  the  live  steam  pipe  through  a  2^4  inch  con- 


FIG.  79. 

Details  of   Rogers  Automatic  Reducing  and  Intercepting  Valves. 
Intercepting  Valve  Open. 

nection.  The  net  area  of  the  upper  side  of  the  valve  B  is 
8.30  square  inches,  while  that  of  the  under  side  of  piston  A  is 
3. 96  square  inches.  The  chamber  <2»  above  piston  A,  opens 
to  the  atmosphere  through  port  X,  so  that  any  leakage  past 
the  piston  will  not  interfere  with  the  free  action  of  the 
valve.  Neglecting  friction,  the  valve  will  open  when  the 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


175 


pressure  beneath  the  valve  drops  below  52  per  cent,  of  the 
live  steam  pressure  in  the  valve  chamber  /,  thus  admitting 
live  steam  to  the  passage,  which  leads  to  the  intercepting 
valve. 

The  opening  of  this  reducing  valve  is  controlled  by 
the  position  of  the  reverse  lever,  the  arrangement  being 
such  that  the  reducing  valve  can  open  only  when  the  reverse 
lever  is  in  the  extreme  backward  or  forward  gear.  Refer- 


FIG.  80. 
Rogers  Automatic  Intercepting  Valve  —  Details  of  Cab  Connections. 

ring  to  Fig.  79,  it  will  be  seen  that  the  upper  end  of  the  stem 
F  of  the  reducing  valve  is  slotted  to  receive  the  short  arm 
at  G.  This  arm  is  mounted  on  a  short  shaft,  to  which  is 
keyed  a  longer  arm  //,  the  end  of  which  drops  nearly  to  the 
centre  of  the  smoke  box.  Attached  to  this  arm  will  be  seen 
a  rod  leading  back  to  the  mechanism,  shown  in  Fig.  So. 
This  device  is  actuated  by  an  independent  reach  rod  from 
the  reverse  lever,  Fig.  81.  The  shape  of  the  curved  slot  on 
this  mechanism  is  such  that  when  in  mid-gear  the  arm  G 
lifts  on  the  valve  stem  F  of  the  reducing  valve  with  such 
force  as  to  prevent  its  opening,  but  when  in  extreme  for- 
ward or  backward  gear,  the  tension  of  this  rod  is  released 
by  the  friction  wheel  A' ,  Fig.  80,  passing  into  the  incline  of 
the  curved  slot  at  either  end,  then  the  arm  G  drops  to  such 
a  position  as  to  allow  the  valve  to  open  or  remain  closed, 
according  to  the  pressures  in  and  befow  the  reducing  valve. 


1 76 


COMPOUND    LOCOMOTIVES. 


The  steam,  after  passing  through  the  reducing  valve, 
flows  through  the  2  inch  pipe  L  to  the  intercepting  valve. 
The  valve  proper  consists  of  a  plain  flap  valve  0  which 
closes  diagonally  across  the  receiver  pipe  in  such  a  way  as 
to  prevent  the  steam  admitted  to  the  1.  p.  cylinder  from 
backing  up  against  the  h.  p.  piston  and  reducing  its 
power.  This  flap  valve  is  con- 
nected to  a  hollow  piston  T  by 
means  of  the  link  U.  Around 
the  wall  of  the  cylinder  in 
which  the  hollow  piston  T  is 
loosely  fitted  is  an  annular 
steam  chamber  E  E  connected 
with  the  pipe  L.  Through  this 
cylinder  wall  there  are  eight 
y%  inch  holes  at  /  /  and  through 
the  wall  of  the  hollow  piston  T\ 
there  are  also  eight  holes, 
inches  diameter  at  K  K,  which, 
when  the  piston  T  moves  out- 
ward, correspond  with  holes  / 
/,  and  steam  from  E  will  then 
pass  through  into  T.  T  also 
has  eight  T9^  holes  M  M  at  its 
inner  end,  and  as  these  holes, 
when  the  intercepting  valve  is  FIG.  81. 

Closed,  are   outside    of    the    end      Details   of     Cab    Connections  — 

of  the  cylinder,  steam  will  pass  Rogers  IntercePtins  Valve- 
out  through  them  into  the  space  N  below  the  intercepting 
valve  and  on  to  the  1.  p.  steam  chest.  The  head  IV,  on 
the  back  end  of  plunger  cylinder,  Fig.  79,  is  chambered 
out  as  shown  at  5  5.  In  the  back  end  of  the  hollow 
piston  T  is  a  solid  plunger  P.  This  plunger  extends 
through  a  hole  Y  in  the  inner  wall  of  the  head  into  the 
chamber  5  5  fitting  loo'sely  in  Y.  From  the  annular  space 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  177 

E  E  through  the  inner  wall  of  the  head  at  ZZ  are  two  holes 
(one  top  and  one  bottom)  -^  inch  diameter  into  the  cham- 
ber vS  *S  for  the  passage  of  steam  to  operate  on  the  plunger 
P  in  closing  the  intercepting  valve  0.  The  dimensions 
of  these  parts  are  as  follows : 

Diameter  of  the  hollow  piston  T  outside,  3  inches. 
11  "  "       "  inside,  2^  inches. 

Stroke  to  close  0,  about  5  inches. 
Diameter  of  plunger  P,  i  ^  inches. 

When  the  parts  are  in  the  position  shown  in  Fig.  79, 
steam  is  admitted  through  the  pipe  L  to  the  annular  cham- 
ber E,  but  as  the  holes  /  /  do  not  correspond  with  the 
holes  in  the  wall  of  7",  steam  can  only  pass  through  the 
two  holes  Z  Z  into  5  S,  where  operating  on  the  end  of  the 
plunger  P  it  causes  the  piston  T  to  move  outward  closing 
the  intercepting  valve,  and  at  the  same  time  bringing  the 
holes  K  Km  correspondence  with  the  holes  //and  allow- 
ing steam  from  the  pipe  L  to  pass  through  the  hollow 
piston  T  out  at  the  holes  M  M  at  its  end  into  N  and  on  to 
the  1.  p.  steam  chest.  The  object  of  wire-drawing  the  steam 
through  the  small  holes  Zzfand  to  have  it  operate  on  the 
comparatively  small  area  of  P  (about  2.4  square  inches) 
in  closing  the  intercepting  valve,  is  to  cause  as  slow  a 
movement  of  the  piston  T  and  as  light  a  shock  in  seating 
the  valve  as  practicable.  There  are  no  steam-tight  joints  or 
packing  in  any  of  the  moving  parts  for  closing  the  intercept- 
ing valve.  Whenever  the  valve  B  of  the  reducing  arrangement 
is  closed,  no  live  steam  can  get  to  the  1.  p.  cylinder.  To 
permit  the  piston  T  to  go  back. to  the  position  shown,  when- 
ever the  pressure  becomes  equal  on  both  sides  of  the  inter- 
cepting valve,  without  resistance,  leakage  holes  are  provided 
at  C  and  D  and  by  these  holes  and  holes  Z  Z  steam  can 
pass  through  from  N  to  T  to  5  and  to  L.  These  holes 
also  prevent  slight  differences  in  pressure  between  TV  and  L, 
from  causing  unnecessary  movement  of  the  piston  T. 


178  COMPOUND    LOCOMOTIVES, 

The  locomotives  that  have  been  built  with  this  starting 
gear  are  given  in  Table  C  C,  Appendix  R. 

102.  The  Baldwin  Locomotive  Works  System. — Figs. 
82,  83,  and  84,  show  the  automatic  intercepting  valve  and 
starting  apparatus  devised  by  the  Baldwin  Locomotive 
Works  for  a  two-cylinder  receiver  compound  for  the  ele- 


FIG.  82. 

Baldwin  Automatic  Intercepting  Valve  —  Cross  Section  Through  Cylinders. 

vated  road  of  the  Chicago  &  South  Side  Rapid  Transit 
Railroad  Company,  Chicago.  Fig.  82  shows  how  the  steam 
passes  from  the  boiler  to  the  h.  p.  cylinder  through  the 
steam  passage  in  that  cylinder.  Opening  out  of  this  pas- 
sage is  a  starting  valve  shown  in  detail  in  Fig.  84,  which  is, 
in  fact,  a  reducing  valve,  which  does  not  permit  the  pressure 
in  the  receiver  to  exceed  100  pounds.  The  boiler  pressure 
is  1 80  pounds.  Whenever  there  is  180  pounds  of  steam 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


179 


pressure  in  the  h.  p.  steam  chest  and  the  pressure  in  the 
receiver  is  less  than  100  pounds,  the  reducing  valve  opens 
and  steam  is  admitted  through  a  pipe  into  the  receiver. 
The  reducing  valve  is  a  single  seated  valve  moved  by  an 
annular  piston,  all  of  which  is  cast  in  one  piece,  as  shown 


FIG.  83. 
Baldwin  Automatic  Intercepting  Valve  —  Side  Elevation. 

in  Fig.  84.  As  the  piston  rises  and  falls  under  the  varia- 
tions in  steam  pressure,  the  reducing  valve  is  opened  and 
shut. 

In  the  smoke  box  is  an  automatic  intercepting  valve 
which  is  opened  like  other  automatic  intercepting  valves  by 
the  exhaust  from  the  h.  p.  cylinder.  This  intercepting 
valve  is  a  simple  piston  moving  vertically  in  a  cylinder 
formed  by  the  inner  casing  of  a  thimble  fitted  into  the 


i8o 


COMPOUND    LOCOMOTIVES. 


receiver.  Above  the  piston  there  is  atmospheric  pressure, 
and  below  the  piston  the  pressure  in  the  receiver.  Hence, 
the  intercepting  valve  is  always  open  when  there  is  pressure 
enough  in  the  receiver  to  lift  the  valve  which  is  in  the 
form  of  a  plunger.  The  valve  is  rather  heavy  and  drops 


FIG.  84. 
Baldwin  Automatic  Intercepting  Valve  —  Detail  of  Reducing  Valve. 

whenever  the  pressure  in  the  receiver  is  reduced  by  the 
closing  of  the  throttle  of  the  engine.  In  practical  operation 
the  weight  and  area  of  this  intercepting  valve  is  so  arranged 
that  it  will  keep  shut  until  the  engine  has  made  one  revolu- 
tion or  less,  after  which  the  pressure  in  the  exhaust  pipe 
of  the  h.  p.  cylinder  has  accumulated  to  an  amount  that 
will  lift  the  valve  and  permit  the  engine  to  work  compound. 


CHAPTER    XVI. 

DESCRIPTION  OF  TWO  -  CYLINDER  RECEIVER  COMPOUNDS 
WITH  AUTOMATIC  STARTING  GEAR  AND  WITHOUT  SEP- 
ARATE EXHAUST  FOR  HIGH -PRESSURE  CYLINDER  AT 
STARTING  AND  WITHOUT  INTERCEPTING  VALVE.  THE 
LINDNER  SYSTEM;  THE  COOKE  LOCOMOTIVE  WORKS 
SYSTEM;  THE  GOLSDORF  (AUSTRIAN)  SYSTEM. 

103.  The  Lindner  System. — This  system  is  not  strictly 
automatic,  and  perhaps  has  some  advantages  for  that  reason  ; 
however,  when  the  engine  is  operated  in  the  usual  way  by 
the  locomotive  engineer,  the  system  is  practically  auto- 
matic. It  is  only  in  the  extreme  forward  and  back  position 
of  the  reverse  lever  that  steam  is  admitted  directly  from 
the  boiler  to  the  1.  p.  cylinder,  and  as  the  engines  are  gen- 
erally run  only  for  the  first  two  or  three  revolutions  with 
the  reverse  lever  in  the  extreme  notches,  it  is  evident  that 
under  ordinary  conditions  the  engineer  would  cut  out  the 
admission  of  steam  directly  from  the  boiler  to  the  1.  p.  cylin- 
der by  hooking  up  the  reverse  lever.  If  it  was  desired  to 
use  boiler  steam  in  the  1.  p.  cylinder  for  a  longer  period, 
it  is  only  necessary  to  allow  the  reverse  lever  to  remain 
in  the  extreme  notch.  The  admission  valve  is  shown  by 
Fig.  85.  C  is  the  receiver,  E  is  a  small  pipe  connecting 
the  receiver  and  the  main  steam  pipe,  and /is  the  starting 
valve,  which  has  two  ports,  H  and  /,  formed  in  it  at  right 
angles.  The  lever  K  by  which  the  valve  is  operated  is  con- 
nected to  the  reach  rod,  and  the  proportions  are  such  that 
K  turns  through  ninety  degrees,  as  indicated  in  the  figure 
when  the  reverse  lever  is  moved  from  one  extreme  position 
to  the  other.  The  effect  is  that  steam  from  the  boiler  is 
admitted  to  the  receiver  when  the  valve  motion  is  in  either 

181 


182 


COMPOUND    LOCOMOTIVES. 


the   extreme   forward   gear  or  the  extreme  backward  gear, 
and  the  cock  is  closed  for  intermediate  positions. 

Another  feature  of  the  Lindner  system  is  the  introduction 
of  two  small  ports,  see  Fig.  87^,  of  small  area  in  the  h.  p.  slide 


FIG.  85. 
Lindner  Starting  Valve- — General  Form. 

valve,  which  are  so  located  that  when  the  valve  covers  the 
steam  port,  at  one  end  of  the  h.  p.  cylinder,  as  after  cut-off 
takes  place,  that  end  of  the  cylinder  is  connected  by  means 
of  one  of  these  small  ports  with  the  exhaust  side  of  the  valve 
and  thus  with  the  receiver.  The  effect  is  to  admit  steam  at 
receiver  pressure  to  the  end  of  the  h.  p.  cylinder,  which 
is  covered  by  the  slide  valve,  and  as  the  other  end  is  then 
open  to  the  exhaust  and  hence  to  the  receiver  pressure,  the 
pressure  on  the  two  sides  of  the  h.  p.  piston  is  partially 
equalized.  In  other  words,  the  effective  back  pressure  on 
the  h.  p,  piston  is  more  or  less  reduced,  so  that  it  offers 
less  resistance  in  starting.  This  device  is  useful  in  starting 
only  for  such  piston  positions  as  lie  between  full  cut-off 
and  the  end  of  the  stroke. 

The  effect   of    the  Lindner    starting    gear  will  depend 
somewhat  upon  whether   or  not   a  relief  valve  is  provided 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  183 

to  limit  the  maximum  pressure  in  the  receiver.  If 
this  receiver  pressure  is  equal  to  ^  of  the  boiler  pressure, 
with  a  cylinder  ratio  of  2,  the  effect  of  the  starting  valve 
is  to  enable  the  engine  to  start  with  very  nearly  the  same 
distribution  of  pressures  on  the  pistons  as  would  be  found 
when  it  is  working  as  a  compound  in  full  gear.  The  result- 
ing rotative  efforts  will  then  be  represented  by  a  curve  such 
as  the  full  line  curve  in  Fig.  30,  the  ordinates  or  actual 
pressures,  however,  being  less  than  those  for  the  single 
expansion  engine  in  about  the  proportion  of  113  to  150, 
with  boiler  pressures  of  170  and  150  pounds. 

If  the  receiver  pressure  is  allowed  to  become  higher 
than  y^  the  boiler  pressure,  the  back  pressure  on  the  h.  p. 
piston  is  increased  proportionately,  and  the  result  is  that 
the  power  of  the  h.  p.  cylinder  is  reduced,  while  that  of 
the  1.  p.  cylinder  is  increased.  The  advisability  of  using 
the  higher  pressure  depends  upon  the  positions  of  the  cranks 
at  starting.  If  the  1.  p.  crank  is  at  a  dead  point,  the  maxi- 
mum effort  will  be  obtained  by  not  admitting  any  steam  to 
the  receiver  at  the  instant  of  starting,  but  before  the  engine 
has  made  ^  of  a  revolution  some  pressure  in  the  receiver 
will  be  necessary  to  enable  the  1.  p.  piston  to  act.  The 
other  extreme  is  when  the  h.  p.  crank  is  at  a  dead  point  in 
starting.  When  this  is  the  case,  the  1.  p.  crank  being  then 
on  the  half  centre,  full  boiler  pressure  cculd  be  advan- 
tageously used  in  the  1.  p.  cylinder,  with  the  result  of 
obtaining  a  rotative  effort  about  4  times  as  great  as  in  a 
single  expansion  engine  starting  with  the  same  crank  posi- 
tions. But  similarly  to  the  first  case,  the  receiver  pressure 
should  be  reduced  almost  as  soon  as  the  engine  begins  to 
move,  or  else  the  h.  p.  piston  will  be  practically  thrown  out 
of  action,  and  the  engine  might  be  stalled  after  making  ^ 
of  a  revolution. 

It   appears,  then,   that   with   this    starting  valve  and   a 
properly  loaded    relief  valve   on  the  receiver  the   starting  is 


184  COMPOUND    LOCOMOTIVES. 

very  simple ;  but  the  power  is  less  than  that  of  the  single 
expansion  engine  having  cylinders  of  the  same  size  as 
the  h.  p.  cylinder  of  the  compound,  the  boiler  pressures 
being  170  and  150  pounds,  respectively.  With  no  safety 
valve,  the  utility  of  the  device  depe'nds  upon  the  position  of 
the  crank  and  the  judgment  of  the  engineman,  66. 

104.  A  Modification  of  the  Lindner  System. — The 
latest  form  of  the  Lindner  system  is  a  modification  of  the 
first.  » It  consists  of  running  the  pipe  which  formerly  led 
from  the  four-way  cock  to  the  receiver,  into  the  side  of  the 
steam  chest.  At  this  point  is  formed  a  small  valve  seat 
over  which  rides  a  flat  valve  without  ports,  which  is  attached 
rigidly  to  the  valve  yoke.  This  valve  is  made  of  such 
length  that  when  steam  is  not  wanted  in  the  1.  p.  cylinder 
for  useful  effect  in  starting,  it  is  shut  out  by  the  valve,  and 
is  not  permitted  to  enter  the  receiver  and  back  up  against 
the  h.  p.  piston.  By  it  steam  can  be  shut  out  of  the  receiver 
when  it  is  advantageous  to  do  so.  It  operates  in  the  same 
general  way  as  an  intercepting  valve,  but  has  the  advantage 
of  being  capable  of  regulation  to  a  greater  degree.  This 
is  the  device  used  on  the  present  Lindner  engines  and  on 
the  Pennsylvania  and  C.,  B.  and  Q.  compounds  illustrated 
in  106  and  107. 

A  further  modification  of  the  Lindner  system  is  some- 
times made  for  locomotives  having  two  h.  p.  cylinders  and 
one  receiver  common  to  both,  and  for  express  engines  hav- 
ing large  driving  wheels  and  comparatively  small  cylinder 
power.  This  modification  consists  in  admitting  steam,  at 
starting,  to  the  pipe  leading  to  the  1.  p.  steam  chest,  through 
a  small  auxiliary  port  in  the  throttle  valve,  in  such  a  way 
that  steam  is  admitted  to  the  h.  p.  steam  chest  through  the 
throttle  valve  in  the  regular  way,  before  the  steam  is  admit- 
ted from  the  boiler  through  the  small  auxiliary  port  in  the 
throttle  valve,  to  the  pipe  leading  to  the  1.  p.  chest.  In 
this  way  full  pressure  is  admitted  to  the  h.  p.  steam 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  185 

chest  before  steam  is  admitted  to  the  auxiliary  pipe  leading 
to  the  1.  p.  steam  chest.  The  object  of  this  is  to  give  full 
pressure  to  the  h.  p.  piston  when  that  piston  has  to  start 
the  engine  before  any  steam  is  admitted  to  the  1.  p.  steam 
chest  or  receiver.  This  arrangement  is  easily  adapted  for 
throttles  in  the  form  of  a  slide  valve,  but  is  difficult  to 
apply  to  engines  having  a  double  poppet  valve. 

105.  The  Lindner  System   as   Used  on  the   Saxon 
State    Railroad;    The    Meyer -Lindner   Duplex   Com- 
pound.— A    four-cylinder  compound   of    the  Duplex    type 
has  been  built  for  the  Saxon  State  Railroad  by  the   Chem- 
nitz Engine  Works  with  the    Lindner  starting  gear.     The 
engine  is  known  as  the  Meyer-Lindner  Duplex  Compound. 
It  is  in   reality  a  double  two-cylinder   compound   with   re- 
ceiver, there  being  two  h.  p.  cylinders  on  one  motor  truck, 
which  exhaust  into   a  common  receiver  which  feeds  two  1.  p. 
cylinders    on    the    other  motor  truck.      The    ratio    of    the 
cylinders  is  2.35.     It  is  claimed  for  duplex  engines  of  this 
type,  as  it  is  for  the  Mallet  duplex  engines,  that  if  the  1.  p. 
driving  wheels  slip  they  will  be   stopped  at   once,   because 
while  the  slipping  is  going  on  the  steam  required    for  the 
1.  p.  pistons  will  exceed  the  amount  delivered  from  the  h.  p. 
cylinders,  and  the  turning  moment  on  the  driving  wheels 
of  the  1.  p.  truck  will  thus  be  decreased.      In  the  same  way, 
if  any  slip  should  occur  with  the  h.  p.   truck  wheels,  it   will 
quickly  be   stopped,   because  then   more   steam  would    be 
going  from  the  h.  p.  cylinders  than  the  1.  p.  cylinders  could 
receive,  and  there  would  be  a  rapid  increase   of  back   pres- 
sure from  the  receiver,  with   a  corresponding  decrease  of 
the  power  exerted  on  the  drivers. 

106.  The  Lindner  System  on  the  Chicago,  Burlington 
&  Quincy  Railroad. — Two  compound  locomotives  of  the 
Mogul  type  have  been  built  by  the   Chicago,  Burlington   & 
Quincy    Railroad   at   the  Aurora    shops,    from    designs  of 
Mr.   William   Forsyth,    Mechanical  Engineer   of  that   road. 


1 86 


COMPOUND    LOCOMOTIVES. 


The  first  engine  had  the  early  form  of  the  Lindner  gear, 
that  is,  without  the  ports  in  the  sides  of  the  steam  chest 
of  the  1.  p.  cylinder  over  which  the  fixed  valve  on  the 
side  of  the  valve  yoke  passes.  This  locomotive  has  given 
excellent  service  since  it  was  first  built.  It  has  now  the 


FIG.  86. 
Lindner  Starting  Valve  on  C.,  B.  &  Q.  Compound. 

latest  form  of  Lindner  gear  except  the  connection  to  the 
throttle.  Figs.  35  and  36  show  the  general  arrangement  of 
cylinders,  receiver  and  the  pipe  to  the  starting  valve,  and 
Figs.  86,  86#,  87  and  87*2  show  the  valves  and  their  applica- 
tion to  the  engine  in  question.  Figs.  86,  S6a  and  87  show 
the  application  of  the  starting  valve  to  the  1.  p.  steam  chest 
and  cylinder  saddle,  and  also  the  fixed  valve  on  the  valve 
yoke  which  keeps  the  admission  port  for  live  steam  into 
the  1.  p.  cylinder  closed,  except  when  it  is  desired  that  steam 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


i87 


should  be  admitted.     Full  control  of  the  admission  of  steam 
into  the  1.  p.  cylinder  is  obtained  in  this   way.     Fig.  S?a 


FIG.  86a. 

Lindner  Starting  Valve  on  C.,  B.  £  Q.  Compound — Section. 


FIG.  87. 
Lindner  Starting  Valve  on  C.,  13.  &  Q.  Compound — End  View, 

shows  the  h.  p.  steam  valve  in  section,  and  indicates  how 
the  small  balancing  ports  used  with  the  Lindner  system  are 
introduced  in  the  h.  p.  steam  valve.  Figs.  35  and  36  give  the 


i88 


COMPOUND    LOCOMOTIVES, 


location  of  the  receiver  and  the  piping  for  the  starting  valve. 
The  starting  valve  is  connected  by  a  rod  with  a  supple- 
mentary vertical  arm  on  the  reverse  shaft.  This  is  shown 
in  Figs.  35  and  S6a.  With  this  arrangement  the  locomo- 


FIG.  Sya. 
Main  Steam  Valve  of  Lindner  Compound  on  C.,  B.  &  Q. 

tive  starts  freight  trains  in  regular  service,  and  all  ordinary 
passenger  trains,  without  difficulty.  The  C.,  B.  &  Q.  road 
adopted  this  arrangement  on  account  of  its  simplicity. 
The  second  engine,  with,  the  compound  system,  is  also  built 
with  this  device. 

107.  The  Lindner  System  on  the  Pennsylvania  Rail- 
road.— A  very  interesting  compound  on  the  Lindner  system 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


189 


has  been  built  by  the  Pennsylvania  Railroad  at  the  Altoona 
shops  from  the  design  of  Mr.  Axel  S.  Vogt,  Mechanical 
Engineer.  The  engine  was  built  for  the  heaviest  class  of 
passenger  service,  and  has  been  in  service  but  a  short  time 


Class-T-Compound 
200  Ibs.  Pressure 


t8ii:___ IL_         !~7"T8-   -j 


FIG.  88. 

Pennsylvania  Compound  with  Lindner  Starting  Gear  —  Side 
Elevation  of  Engine. 


LJ_L 


Line  of  Rail 


FIG.  89. 

Pennsylvania  Compound  with  Lindner  Starting  Gear  —  End 
Elevation  of  Engine. 

at  this  writing.  Some  changes  were  required  in  the  valve 
motion  and  smoke  box  apparatus  to  improve  the  steaming 
of  the  engine,  and  she  has  been  taken  from  service  to  have 
these  changes  made.  This  is  undoubtedly  the  heaviest  four 


I QO  COMPOUND    LOCOMOTIVES. 

coupled  compound  locomotive  yet  made.  The  general  type 
of  the  engine  is  shown  in  Figs.  88  and  89.  The  following 
are  the  principal  dimensions: 

Weight  of  Engine  Empty 130,000  Lbs. 

"       on  Drivers 84,000     " 

"        "   Truck 46,000     " 

"       of  Engine  in  Working  Order 145,500     " 

"       on  1st  pair  Drivers 48,500     " 

"2nd    "         "        46,700     " 

"  Truck 50,300     " 

Tender  Fitted  with  Scoop. 

Capacity  of  Tender — Water 3,ooo  Gals. 

"      —Coal I5,ooo  Lbs. 

Weight      "         "     —Empty 37»ioo     " 

"             "         "      — Loaded 77,000     " 

Spread  of  Cylinders 79  Inches 

Distance  bet.  Centre  of  Frames 42       " 

Width  of  Cab 9  ft.  7  in. 

Height  of  Cab  Roof  from  Rail  (Centre) 14  ft.  o  in. 

Inside  Length  of  Fire-Box 9  ft.  o  in. 

"      Width   "         "         40  Inches 

Number  of  Tubes 289 

Length    "       "      1 1  ft.  9^  in. 

Outside  Diameter  of  Tubes i%  Inches 

Diameter  of  Drivers,  outside  of  tires 84  Inches 

Diameter  of  Truck  Wheels,  outside  of  tires 42      " 

Fire  Box  of  Belpaire  type. 

Grate  area 30  square  feet 

Fire  Box  Heating  Surface 159 

Tube  Heating  Surface 1661      " 

Total  Heating-  Surface 1820      " 

Working  Boiler  Pressure,  by  gauge 200  Ibs. 

Safety  Valve  set  at 205    " 

High-Pressure  Cylinders K)l/2  X  28  in. 

Low-Pressure  Cylinders 31  X  28  in. 

The  main  valves  are  of  the  piston  type,  and  both  are 
12%  inches  in  diameter  with  a  maximum  travel  of  7  inches 
in  full  gear,  and  are  placed  between  the  frames  in  the  saddle. 
The  section  of  the  valves  is  reduced  near  the  centre  of  the 
length,  and  the  annular  cavity  thus  formed  communicates 
with  the  live  steam  pipe  in  the  h.  p.  valve  and  with  the  receiver 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  IQI 

in  the  1.  p.  valve,  so  that  the  steam  for  both  cylinders  is 
admitted  at  the  centre  and  discharged  at  the  ends  of  the 
valves.  The  steam  admission  opening  to  both  valves  is  5^ 
inches  wide,  and  the  steam  ports  leading  from  valve  liner  to 
both  cylinders  are  2^  inches  wide  ;  making  allowance 
for  the  bridges  crossing  the  port  openings  the  actual  length 
of  the  steam  ports  in  the  valve  seat  of  both  cylinders  is  29 
inches.  The  receiver  pipe  is  made  of  copper  and  has  an 
internal  diameter  of  8  inches. 

The  cut-off  in  full  forward  gear  is  22  inches  or  78.6  per 
cent,  of  the  stroke  in  h.  p.  cylinder,  and  23.5  inches  or  83.9 
per  cent,  of  stroke  in  1.  p.  cylinder.  The  lap  on  steam  side 
is  1.53  inches  on  the  h.  p.  valve,  and  1.31  inches  on  the  1.  p. 
valve.  The  clearance  or  negative  lap  on  exhaust  side  is 
0.625  inch  on  h.  p.  valve  and' 0.75  inch  on  1.  p.  valve. 

The  steam  admission  leads  are  as  follows : 

FULL    FORWARD    GEAR. 

H.  p.  front,  0.115" 
H.  p.  badk,  0.23" 
L.  p.  front,  0.25" 
L.  p.  back,  0.125" 

FULL    BACK    GEAR. 
H.  p.  front,  negative  0.70 
H.  p.  back,  negative  0.55 
L.  p.  front,  negative  0.47 
L.  p.  back,  negative  0.70 

When  in  full  forward  gear  the  maximum  port  openings 
to  steam  are : 

H.  p.  cylinder,  1.97 
L,  p.  cylinder,  2.19 

and  to  exhaust : 

H.  p.  cylinder,  full 
L.  p.  cylinder,  full 

When  cutting  off  at  50  per  cent,  stroke  the  port  openings  to 
steam  are : 

H.  p.  cylinder,  0.98 
L.  p.  cylinder,  1.12 


COMPOUND    LOCOMOTIVES, 
and  to  exhaust  : 

H.  p.  cylinder,  full 
L.  p.  cylinder,  full 

The  radius  of  the  link  is  51  inches  and  length  of  the 
connecting  rod  7  feet  ^8  inches.  The  receiver  volume  is 
26672  cubic  inches,  the  volume  of  h.  p.  cylinder  8362.2 
cubic  inches  and  its  clearance  1045  cubic  inches.  The  vol- 
ume of  the  1.  p.  cylinder  is  21 134.4  cubic  inches  and  its  clear- 
ance 1438.7  cubic  inches.  H.  p.  cylinder  clearance  is  12.28 
per  cent.;  1.  p.  cylinder  clearance  is  6.8  per  cent.;  ratio 
of  receiver  volume  to  h.  p.  cylinder  volume  is  3.2.  The 
Lindner  device,  consisting  of  a  four-way  plug  cock,  is  applied 
to  this  engine,  the  equalization  ports  in  the  h.  p.  valve  are 
each  y3^  inches  X  I  inch  and  the  controlling  port  in  the  1.  p. 
valve  is  -fa  inches  X  I  ^  inches.  The  pipe  which  admits 
steam  to  the  four-way  cock  is  connected  directly  to  the 
main  steam  pipe  in  the  smoke  box,  as  has  been  described 
before  for  the  Lindner  system,  106. 

This  engine  has  5^-inch  inside  clearance  or  negative  lap 
for  h.  p.  cylinders,  J^-inch  for  1.  p.  cylinders,  and  every 
endeavor  has  been  made  to  get  the  best  possible  steam  dis- 
tribution. The  receiver  is  unusually  large,  and  so  far  as 
can  be  seen  at  this  time  the  design  of  cylinder  apparatus  is 
one  that  should  give  a  superior  steam  distribution,  and  thus 
be  very  economical.  Owing  to  the  very  liberal  clearance, 
or  negative  lap,  and  the  large  ports  used,  the  cylinder 
power  at  high  speeds  should  be  greater  than  any  other 
compound  engine  locomotive  built  up  to  this  time.  It  is 
intended  with  this  engine  to  regulate  the  power  with  the 
reverse  lever  and  not  with  the  throttle  lever  at  high  speeds. 

108.  The  Cooke  Locomotive  Works  System. — An 
experimental  engine  was  built  by  the  Cooke  Locomotive 
Works,  Paterson,  N.  J.,  to  determine  the  value  of  the  com- 
pound system  described  in  the  following :  It  was  a  two- 
cylinder  compound  with  receiver.  The  cylinders  were  19 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


193 


and  27  x  24  inches.  No  intercepting  valve  was  employed. 
The  details  of  the  starting  gear  are  shown  in  Figs.  90  and 
91.  The  volume  of  the  receiver  was  practically  the  same 
as  that  of  the  h.  p.  cylinder.  In  starting,  steam  is  let  into 


FIG.  90. 
Cooke  Starting  Gear. 

the  receiver  from  the  dome,  by  opening  a  valve  A  which  is 
connected  to  the  throttle  lever.  Steam  passes  through  a 
reducing  valve  B  and  is  kept  by  this 
valve  to  the  proper  pressure.  Fig. 
91  shows  the  connection  to  the 
throttle  lever.  When  the  throttle  is 
closed,  the  small  lever  C  can  be 
operated  and  the  valve  A  opened, 
but  when  the  throttle  is  open  the 
valve  C  cannot  be  opened  also,  as 
the  lever  C  is  then  made  inoperative 
by  the  disengagement  of  its  cam 
FIG.  91.  connection  with  rods  leading  to  the 

Cab  Connection,  Cooke  Gear,  throttle  lever. 


194 


COMPOUND    LOCOMOTIVES. 


109.  The  Golsdorf  (Austrian)  System. — The  Austrian 
Government  has  made  an  examination  of  all  the  systems  of 
compound  locomotives  in  use.  These  examinations  were 
made  by  the  mechanical  engineers  connected  with  the  State 
Railway  system.  The  reports  advised  that  the  increased 
cost  of  maintenance  of  existing  types  of  compounds  would 
be  too  great  under  the  conditions  on  Austrian  roads,  and 
the  matter  was  dropped  for  a  time  ;  but  was  taken  up  again 
after  the  invention  of  a  simple  starting  apparatus  by  C. 
Golsdorf,  a  mechanical  engineer  connected  with  the  State 
Railways.  In  Austria  the  coal  is  inferior,  and  the  Govern- 
ment reports  state  that  but  3^  pounds  of  water  are  evap- 
orated per  pound  of  coal  used.  This  coal  being  inferior 


FIG.  92.  FIG.  93. 

Golsdorf  Starting  Gear — Plan  of  Valve  Seat  and  Valve. 

and  expensive,  the  advantage  of  compounding  is  somewhat 
greater  in  Austria  than  in  other  parts  of  Europe.  The 
saving  by  compounding  was  found  to  be  about  18  per  cent. 
Golsdorf's  device  is  constructed  as  follows  :  Leading  from 
the  main  steam  pipe  is  a  i-inch  copper  steam  pipe  which 
connects  with  a  fitting  on  the  1.  p.  steam  chest,  at  which  the 
current  of  steam  is  divided  into  ^-inch  pipes  which  lead 
to  two  ports  constructed  in  bridges  in  the  main  steam  port, 
as  shown  in  Fig.  92.  These  ports  are  about  ^  inches  long 
by  ^  inches  wide  in  the  direction  of  the  valve  travel. 
The  steam  valve,  Fig.  93,  has  a  bridge  across  its  centre, 
as  shown,  which  covers  the  small  steam  ports.  This 
describes  the  entire  construction  or  the  compound  starting 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 

gear  which  is  in  the  1.  p.  valve  seat.  The  h.  p.  valve  seat  is 
constructed  as  usual.  The  valve  motion  is  the  Walscheart, 
which  has  been  chosen  because  it  gives  a  longer  maximum 
cut-off  than  the  ordinary  link  motion.  By  it  is  obtained 
a  maximum  cut-off  of  92  per  cent.  The  operation  of  this 
system  is  as  follows  : 

When  the  reverse  lever  is  in  full  gear,  or  nearly  so,  the 
valve  travel  is  such  as  to  uncover  the  small  port  whenever 
the  1.  p.  cylinder  is  to  furnish  the  power  for  starting,  and  in 
this  way  steam  enters  from  the  main  steam  pipe,  when  the 
throttle  is  open,  to  the  1.  p.  cylinder  steam  chest  and 
receiver.  When  the  start  is  to  be  made  by  the  h.  p. 
cylinder,  the  1.  p.  slide  valve  is  in  such  position  as  to  cover 
the  small  port  and  prevent  the  entrance  of  steam  from  the 
steam  pipe  into  the  1.  p.  cylinder.  When  the  engine  is 
started,  the  driver  hooks  up  the  reverse  lever,  which  reduces 
the  valve  travel  and  the  small  ports  are  not  uncovered. 
With  this  gear,  which  is  not  unlike  the  Lindner,  the  maxi- 
mum starting  power  can  only  be  obtained  during  the  first 
revolution,  or,  more  correctly,  during  a  part  of  the  first 
revolution.  The  first  of  these  engines  was  built  in  1892. 
Since  then  five  others  have  been  ordered.  A  general 
description  of  the  engines  is  given  in  Table  C  C,  Appen- 
dix R. 


CHAPTER    XVII, 

DESCRIPTION  OF  TWO  -  CYLINDER  RECEIVER  COMPOUNDS 
WITH  INTERCEPTING  VALVE  AND  WITH  SEPARATE 
EXHAUST  FOR  HIGH  -  PRESSURE  CYLINDERS  AT  START- 
ING. 

110.  The  Mallet  System. — This  system  is  non-auto- 
matic, by  which  is  meant  that  the  change  from  the  use  of 
h.  p.  steam  in  the  1.  p.  cylinder  to  full  compound  action  is 
made  at  the  will  of  the  engineer  and  not  automatically. 
This  system  has  suitable  valves  so  that  the  engine  may  be 
operated  as  a  single  expansion  engine,  not  only  in  starting 
but  at  any  time  when  in  service.  Such  an  engine,  while 
having  all  the  advantages  ok  compound  working,  possesses 
an  emergency  power  equal,  or  possibly  superior  to,  a  single 
expansion  engine  having  the  same  general  dimensions. 

Figs.  94  to  99,  inclusive,  illustrate  the  arrangement  of 
this  system  as  applied  to  a  converted  six-coupled  engine  of 
the  Western  Switzerland  Railroad. 

In  Fig.  94,  h  and  /  are  the  h.  p.  and  1.  p.  cylinders, 
respectively.  A  is  the  main  steam  pipe  from  the  boiler  to 
the  h.  p.  cylinder,  B  is  the  receiver,  C  is  the  1.  p.  exhaust 
pipe,  D  is  the  starting  valve  which  is  connected  to  the  boiler 
by  the  pipe  E,  F  is  the  intercepting  valve,  and  G  is  the 
exhaust  pipe  from  the  h.  p.  cylinder  when  working  as  a 
single  expansion  engine. 

The  construction  of  the  starting  valve  is  shown  in  Figs. 
95  and  96.  It  consists  primarily  of  a  short  slide  valve  a, 
which,  as  shown,  covers  two  ports  leading  to  the  receiver. 
The  pipe  p  connects  the  starting  valve  chamber  with  the 
main  steam  pipe.  On  the  back  of  the  valve  a  is  an  inverted 
slide  valve  £,  which  slides  on  a  seat  formed  in  the  valve- 

196 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


IQ7 


chest  cover.  A  small  pipe  c  connects  the  starting  valve 
chamber  with  the  intercepting  valve  on  the  other  side  of 
the  smoke  box,  as  shown  at  c,  Fig.  97.  Referring  now  to 


FIG.  94. 
Mailet  Starting  Gear — Arrangement  of  Parts. 


•  FIG.  95. 

Mallet  Starting  Gear — Detail  of  Starting  Valve. 

Fig.  97  it  will  be  seen  that  the  intercepting  valve  consists 
of  two  circular  valves  and  a  piston,  all  being  mounted  on 
one  stem,  and  so  forming  a  sort  of  balanced  double  poppet 
valve.  The  connections  to  the  intercepting  valve  are  as 


IQ8 


COMPOUND    LOCOMOTIVES. 


indicated  in  the  figure,  the  central  opening  connecting  with 
the  h.  p.  exhaust,  the  left  with  the  common  exhaust  nozzle 
and  the  right  with  the  receiver  pipe. 


FIG.  96. 
Mallet  Starting  Gear  —  Detail  of  Starting  Valve. 


FIG.  97. 
Mallet  Intercepting  Valve. 


The  operation  of  these  valves  is  as  follows  :  They  are 
shown  in  the  illustrations  in  the  positions  which  they 
ordinarily  occupy,  or  when  the  engine  is  working  as  a  com- 


4 

TWO-CYLINDER    RECEIVER    COMPOUNDS. 

pound.  Under  these  circumstances  steam  from  the  boiler 
is  admitted  to  the  space  d  back  of  the  piston  e  by  way  of 
the  small  pipe  c,  the  starting  valve  chamber,  and  the  pipe 
p.  The  pressure  thus  acting  upon  the  piston  e  keeps  the 
valve  g  closed  against  the  ordinary  receiver  pressure.  The 
intercepting  valve  can,  of  course,  be  connected  so  as  to  be 
worked  by  hand  in  connection  with  the  starting  valve.  If 
now  the  starting  valve  is  opened,  or  moved  to  the  right  in 
Fig.  95,  steam  from  the  boiler  is  thereby  admitted  to  the 
receiver,  and  at  the  same  time  the  pipe  c  is  placed  in  com- 
munication with  the  atmosphere  by  means  of  the  cavity  in* 
the  top  of  the  starting  valve.  The  pressure  back  of  the 
piston  e  being  thus  reduced,  the  valve  g  is  opened  by  the 
receiver  pressure,  and  the  valve  h  is  closed,  in  which  position 
it  is  retained  by  the  excess  of  the  pressure  in  the  receiver, 
Fig.  97,  or  that  on  the  1.  p.  side  of  the  valve,  over  that 
on  the  h.  p.  side  which  is  now  in  communication  with  the 
exhaust  nozzle.  It  will  be  seen  that  the  locomotive  will 
now  work  as  a  single  expansion  engine,  and  will  continue 
to  do  so  as  long  as  the  starting  valve  is  kept  open.  As 
soon  as  it  is  closed  the  intercepting  valve  will  be  returned 
to  the  position  shown  in  Fig.  97. 

On  the  engine  illustrated  by  Fig.  94,  a  pressure-redu- 
cing valve  is  inserted  between  the  starting  valve  and  the 
receiver.  This  reducing  valve  is  of  the  common  differential 
piston  type,  adjusted  by  springs.  In  addition  to  this  the 
receiver  is  fitted  with  a  spring  safety  valve  loaded  to  70 
pounds  pressure.  It  would  seem  when  a  starting  valve  of 
this  form  is  used  in  conjunction  with  a  safety  valve,  that  the 
introduction  of  a  reducing  valve  is  unnecessary,  as  the 
receiver  pressure  can  be  regulated  by  the  starting  valve. 

111.  The  Early  Form  of  the  Mallet  System.— In 
earlier  designs  Mr.  Mallet  has  combined  the  starting  and 
intercepting  valve  in  one  distributing  valve.  This  is  illus- 
trated by  Figs.  98  and  99.  The  distributing  valve  and  a 


2OO 


COMPOUND    LOCOMOTIVES. 


reducing  valve  are  enclosed  in  a  casing  which  is  fastened 
to  the  smoke  box.  The  main  steam  pipe  is  connected  at  a, 
and  thence  by  a  passage  b,  back  of  the  valves,  to  the  h.  p. 
steam  chest.  An  opening  at  c  admits  steam  from  this  pipe 
to  the  reducing  valve  chamber  and  thence  to  the  distribut- 


FIG.  98. 

Mallet  Distributing  Valve. 


FIG.  99. 
Mallet  Distributing  Valve. 

ing  valve  chamber,  The  distributing  valve  is  a  slide  valve, 
and  covers  three  ports,  as  shown.  Of  these  d  is  the  h.  p. 
exhaust,  e  connects  with  the  receiver,  and  hence  with  the 
1.  p.  steam  chest,  and  g  leads  to  the  exhaust  nozzle.  The 
^alve  is  shown  in  the  position  for  compound  working.  If 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


201 


it  is  moved  forward,  or  to  the  left  in  the  illustrations,  the 
passage  d  is  connected  with  g,  and  the  h.  p.  cylinder 
exhausts  directly  to  the  exhaust  nozzle,  and  at  the  same 
time  by  means  of  the  passages  c  and  e  boiler  steam  at 
reduced  pressure  is  admitted  to  the  receiver  and  the  1.  p 
steam  chest. 


FIG.  100. 
Mallet's  Proposed  Double  Low- Pressure  Cylinder. 


FIG.  101. 
Mallet's  Proposed  Double  Low-Pressure  Cylinder. 

The  earlier  forms  of  intercepting  valves  were  not  wholly 
automatic  in  their  action,  but  required  to  be  closed  by  hand 
before  opening  the  throttle  in  starting.  In  this  form  there 
were  no  small  plungers,  and  the  steam  was  admitted  around 


2O2  COMPOUND    LOCOMOTIVES. 

the  valve  stem  k,  which  was  fluted  for  part  of  its  length  for 
this  purpose.  The  valve  was  also  connected  by  a  bell-crank 
arrangement  to  a  weighted  arm,  which  held  the  valve  open 
and  prevented  rattling  when  running  with  steam  shut  off. 

112.  Preliminary  Work  of  Mallet. — The  earliest  work 
of  real  practical  value  in  compound   locomotive  designing 
was  done  by  Mr.  Mallet.     Two  of  his  most  important  con- 
tributions  to  the  subject  are   the  separate  exhaust   of  the 
h.   p.   cylinder  at   starting,    previously   described,    and    the 
double  1.  p.  cylinder,  Figs.  100  and  101.     The  object  of  this 
double  1.  p.  cylinder  is  to  give  to  the  nominally  two-cylinder 
type  the  necessary  volume  of  1.  p.  cylinder  without  exceed- 
ing the  maximum  width  allowable  for  locomotives. 

113.  Rhode  Island  Locomotive  Works   (Batchellor) 
System.  —  The     Rhode     Island     Locomotive    Works,    or 
Batchellor,  system  is  shown   in    Figs.    102,    103    and    104. 
The  following  is  the  construction  and  operation  :   Fig.  102 
shows  the  front  section  of  intercepting  valve  at  ports  d  and 
e,  also  front  view  of  portion  of  receiver  with  exhaust  valve. 
Fig.  103  shows  side  section  of  intercepting  valve  while  run- 
ning compound.      Fig.  104  shows  side  section  of  intercept- 
ing   valve    when    engine     is    operating    with     independent 
exhaust    for   h.   p.   cylinder.      A    is   the   intercepting  valve 
casing,  B  is  the  reducing  valve,  C  the   oil    dash-pot,  D  is  a 
pipe  from   main  steam   pipe  to  intercepting  valve,  E  is  the 
receiver,  F  is  the  exhaust  valve  leading  to  atmosphere  from 
receiver,  a,  b  and  c  is  the    intercepting  valve  piston,  d  is  a 
port  leading  from  D  to  through  the  casing  of  the  intercept- 
ing valve,  D  being  the   pipe    from   the   main   steam  pipe  to 
intercepting    valve,   e   is   a  port    from     intercepting    valve 
casing  to  the  reducing  valve  B.  There  is  a  port  from  the  inter- 
cepting valve  casing  into   the   passage   leading  to   the  1.  p. 
steam    chest,     m   is   the  crank   which   operates  the  exhaust 
valve  leading  from   the  receiver  to  the  atmosphere,  o  and  o 
are  ports  leading  through  the  exhaust  valve  F  and  its  seat. 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  2O3 


FIG.  102. 

Rhode  Island  Locomotive  Works  (Batchellor)  Starting  Gear  —  Cross  Section 
Through  Intercepting  Valve  and  Separate  Exhaust  Valves. 


FIG.  103. 

Longitudinal  Section  Through  Rhode  Island  Locomotive  Works  (Batchellor) 
Intercepting  Valve  —  Valve  Open. 


2O4  COMPOUND    LOCOMOTIVES. 

The  operation  of  the  device  is  as  foltows  :  The  inter- 
cepting valve  being  in  any  position,  as  in  Fig.  103,  and 
the  exhaust  valve  closed,  the  throttle  being  opened, 
boiler  steam  will  pass  to  the  h.  p.  cylinder  in  the  usual 
manner,  and  also  through  pipe  D  into  the  intercepting 


FIG.  104. 

Longitudinal  Section  Through  Rhode  Island  Locomotive  Works  (Batchellor) 
Intercepting  Valve  —  Valve  Closed. 

valve  A,  causing  the  piston  to  move  into  the  position  shown 
in  Fig.  104.  In  this  position  the  receiver  is  closed  to  the 
1.  p.  cylinder  by  the  piston  C,  and  steam  from  D  passes 
through  ports  d  and  e,  and  reducing  valve  B,  into  the  1.  p. 
steam-chest ;  the  pressure  being  reduced  from  boiler  pres- 
sure in  the  ratios  of  the  cylinder  areas.  The  piston  a-b-c, 
is  so  proportioned  that  it  will  automatically  change  to  the 
compound  position  shown  in  Fig.  103,  when  a  predeter- 
mined pressure  in  the  receiver  E  has  been  reached  by 
exhausts  from  the  h.  p.  cylinder.  The  engine  thus  starts 
with  steam  in  both  cylinders,  and  automatically  changes  to 
compound  at  a  desired  receiver' pressure. 

The  engine  may  be  changed  from  the  compound  system 
to  the  single  expansion  at  any  time,  at  the  will  of  the 
engineer,  by  opening  the  valve  F  connecting  the  receiver  to 
the  exhaust  pipe,  allowing  the  exhausts  from  the  h.  p.  cyl- 
inder to  escape  through  the  nozzle  in  the  usual  manner. 

The  exhaust  valve  .F  is  operated  as  follows:  The  lever 
m,  which  rotates  the  exhaust  valve  F,  is  connected  by  a  rod 
to  a  handle  in  the  cab.  To  run  compound  place  lever  m  as 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  2O5 

" 
shown  on  the  left  in  Fig.  102,   which    closes   ports  o.     To 

run  single  expansion  place  lever  m  as  shown  on  the  right 
in  Fig.  1 02,  the  ports  o  opening  E  to  exhaust. 

It  is  obvious  that,  in  case  of  bad  conditions  of  starting, 
the  engine  may  be  operated  single  expansion  at  the  will  of 
the  engineer  by  opening  the  exhaust  valve  before  starting, 
and  that  upon  its  closure  the  piston  a-b-c  will  automatically 
take  the  compound  position  of  Fig.  103. 

This  system  can  be  used  either  as  automatic  or  non- 
automatic  as  desired. 

The  Rhode  Island  Locomotive  Works  claim  the  follow- 
ing for  their  system  of  starting  gear : 

(1)  Compound   engine  automatically  adapted  to  all    requirements  of    variable 
service. 

(2)  All  necessary  devices  by  which  a  locomotive  may  be  run  at  any  time  and  at 
any  place  on  the  road,  and  for  any  length  of  time  demanded  by  the  service,  as  a  single 
expansion  engine;   each  cylinder  doing  exactly  halt  the  work,  whatever  that  may  be, 
and  without  waste  of  steam. 

(3)  The  engineer,  at  any  time  he  chooses,  may  change  the  engine  into  compound 
working,  permitting  it  to  operate  thus  as  long  as  circumstances  will  require,  and  then 
he  may  change  it  back  again  at  once  into  single  expansion  working.     These  changes 
are  made  as  easily  as  the  engineer  turns  his  hand  to  open  or  close  one  valve,  by  a 
convenient  lever  in  the  cab,  and  can  be  done  when  the  engine  is  standing  or  in 
motion. 

(4)  Great  simplicity  in  form  and  number  of  working  parts,  and  whose  steam-ways 
are  most  uniform  in  section  and  most  direct  in  course  from  boiler  to  point  of  applica- 
tion. 

(5)  Ability  to  run  as  a  single  expansion  locomotive  in  case  of  break  down  with  no 
more  trouble  than  an  ordinary  locomotive. 

The  use  of  an  independent  exhaust  for  the  h.  p.  cylinder 
has  made  these  engines  well  adapted  for  elevated  railroad 
service.  This  company  has  built  on  this  plan  a  number 
of  engines  that  are  in  successful  service,  see  Table  CC, 
Appendix  R. 

114.  The  Richmond  Locomotive  Works  (Mellin) 
System. — This  system  is  strictly  automatic  under  ordinary 
conditions  ;  that  is,  the  use  of  steam  directly  from  the  boiler 
into  the  1.  p.  cylinder,  is  shut  off  whenever  the  exhaust 
pressure  from  the  h.  p.  cylinder  accumulates  in  the  receiver 


2O6  COMPOUND    LOCOMOTIVES. 

to  a  point  where  it  will  actuate  the  automatic  mechanism. 
But  it  also  has  what  the  inventor  calls  an  "emergency" 
valve,  and  by  it  the  engineer  can  open  a  separate  exhaust 
for  the  h.  p.  cylinder  for  a  sufficient  period  at  starting 
to  get  the  train  under  way.  At  this  writing  the  patents 
for  this  device  have  not  been  granted,  and  it  has  been 
deemed  inadvisable  to  publish  the  drawings.  The  fol- 
lowing is,  however,  a  general  description: 

In  the  cylinder  saddle  there  is  a  small  piston  with  a 
dash-pot  connected  to  the  piston  rod  which  controls  an 
intercepting  valve  placed  horizontally.  The  intercepting 
valve  shuts  off  the  steam,  that  is  admitted  to  the  1.  p.  cyl- 
inder at  starting,  from  entering  the  receiver.  Surrounding 
the  small  piston  just  mentioned  is  an  annular  sleeve  or 
piston  which  serves  as  a  reducing  valve.  The  emergency 
valve  consists  of  a  plain,  bevel-seated  valve  attached  to  a 
piston  which  is  connected  on  one  side  to  a  live  steam  pipe 
leading  to  a  valve  in  the  cab.  This  piston  is  returned  to 
its  seat  by  a  spring  on  the  piston  rod.  The  device  operates 
as  follows: 

Steam  from  the  main  steam  pipe  acts  upon  the  annular 
piston  around  the  intercepting  valve  stem  and  forces  the 
intercepting  valve  to  its  seat,  thus  closing  communication 
between  the  1.  p.  cylinder  and'  the  receiver.  At  the  same 
time  the  sleeve  or  annular  piston  opens  a  small  port  which 
admits  steam  to  the  1.  p.  cylinder  directly  from  the  main 
steam  pipe.  This  sleeve  then  acts  as  a  reducing  valve. 
The  intercepting  valve  is  prevented  from  slamming  by  the 
air  dash-pot  on  the  end  of  the  stem.  When  the  intercepting 
valve  is  closed  the  exhaust  from  the  h.  p.  cylinder  accumu- 
lates in  the  receiver,  and  pushes  the  intercepting  valve  back 
to  an  open  position  and  the  engine  works  compound. 

When  it  is  desired  to  work  with  a  separate  exhaust  for 
the  h.  p.  cylinder  the  engineer  opens  a  valve  in  the  cab  and 
admits  steam  back  of  the  piston,  which  is  connected  with 


TWO-CYLINDER    RECEIVER    COMPOUNDS. 


2O7 


the  emergency  valve.  The  pressure  on  the  piston  forces 
the  emergency  valve  open.  This  opens  communication 
from  the  receiver  to  the  atmosphere,  and  gives  a  separate 
exhaust  for  the  h.  p.  cylinder.  When  running,  the  engine 
can  be  changed  from  compound  to  non-compound  by  open- 
ing the  valve  in  the  cab.  This  system  then,  can  be  used  as 
either  automatic  or  non-automatic,  as  desired. 

115.  The  Pittsburgh  Locomotive  Works'  (Colvin) 
System. — Figs  105  to  107  show  the  non-automatic  inter- 
cepting and  reducing  valve  used  by  the  Pittsburgh  LOCO- 


FIG.  105. 

Arrangement  of  Cylinders  and  Intercepting  Valve,  Pittsburgh  Locomotive 
Works  (Colvin)  System. 

motive  Works  on  several  two-cylinder  compounds  which 
they  have  built.  This  reducing  non-automatic  intercepting 
valve  is  placed  in  the  h.  p.  cylinder  saddle,  as  shown  in 
Fig.  105,  and  is  so  arranged  that  the  engineer,  by  moving 
the  lever  in  the  cab,  can  open  an  independent  exhaust  for 
the  h.  p.  cylinder  through  passage  Fig.  106,  to  the 
stack.  When  it  is  desired  to  run  compound  the  lever  is 
again  moved  and  the  intercepting  valve  is  open.  In  Fig. 
107  the  intercepting  and  reducing  valve  are  shown  when  in 
'the  position  to  work  compound. 


208 


COMPOUND    LOCOMOTIVES. 


In  this  system  steam  from  the  steam  pipe  in  the  h.  p. 
cylinder  saddle  passes  to  the  reducing  valve  through  a 
small  passage  shown  in  Figs.  106  and  107.  When  the 
reducing  valve  is  permitted  to  open,  as  it  is  in  Fig.  106  by 
the  removal  of  the  intercepting  valve  to  the  right,  steam 
passes  directly  through  the  reducing  valve  as  shown  by  the 


FIG.  106. 

Pittsburgh  Locomotive  Works  System — Separate  Exhaust  for  High-Pressure 
Cylinder,  Open. 


FIG.  107. 

Pittsburgh  Locomotive  Works — Separate  Exhaust  for  High-Pressure 
Cylinder,  Closed. 

arrows  from  the  h.  p.  steam  pipe  to  the  receiver  thence  to 
1.  p.  cylinder.  The  amount  of  reduction  of  pressure  by  the 
reducing  valve  depends  upon  the  ratio  of  the  areas  of  the 
piston  of  the  reducing  valve  and  the  area  of  the  valve 
itself. 

When   the   engine  is  to  be  run  compound  the  engineer 


TWO-CYLINDER    RECEIVER    COMPOUNDS.  2OQ 

forces  the  intercepting  valve  back  to. the  position  shown  in 
Fig.  107  by  means  of  a  rod  which  is  connected  to  a 
lever  in  the  cab.  The  movement  of  the  intercepting  valve 
to  the  left  forces  the  reducing  valve  to  its  seat  as  shown  in 
Fig.  107  and  permits  the  h.  p.  cylinder  to  exhaust  into  the 
receiver.  When  in  the  non-compound  position,  shown  in 
Fig  1 06,  the  h.  p.  cylinder  exhausts  directly  to  the  atmos- 
phere as  indicated  in  Fig.  105. 

The  engines  that  have  been  built  with  this  gear  up  to 
this  time  are  given  in  Table  C  C,  Appendix  R. 

116.  von  Berries'  Latest  System. — After  a  number  of 
years'  experience  with  automatic  starting  gears  that  give 
increased  power  to  compound  locomotives  during  a  part  of 
the  first  revolution,  Mr.  von  Borries  has  reached  the  impor- 
tant conclusion  that  an  independent  exhaust  with  an  h.  p. 
cylinder,  such  as  used  by  Mallet,  is  necessary  for  two- 
cylinder  receiver  compounds  with  cranks  at  right  angles 
when  the  locomotive  has  to  start  heavy  trains  or  work  on 
comparatively  heavy  grades.  Mr.  von  Borries'  device  for 
accomplishing  this  is  as  follows  : 

A  double  piston  valve  having  a  piston  rod  with  a  reduced 
section,  which  serves  as  a  reducing  valve,  operates  horizon- 
tally in  a  chamber  on  top  of  the  h.  p.  steam  chest.  The 
chamber  has  three  main  passages,  one  leading  to  the  receiver, 
one  leading  to  the  h.  p.  exhaust,  and  a  third  leading  to  the 
atmosphere.  This  last  is  the  independent  exhaust  for  the 
h.  p.  cylinder.  This  chamber  also  has  a  passage  connected 
with  a  comparatively  small  pipe  leading  to  the  h.  p.  steam 
pipe.  Through  this  passage  comes  the  steam  that  goes 
directly  to  the  receiver  and  1.  p.  cylinder  at  starting.  When 
the  piston  is  at  one  end  of  the  stroke  the  exhaust  passage 
from  the  h.  p.  cylinder  to  the  atmosphere  is  open.  When  in 
the  other  extreme  position,  the  separate  exhaust  is  closed 
and  the  passage  is  open  through  which  the  h.  p.  cylinder 
exhausts  into  the  receiver.  The  movement  of  the  piston 


2IO  COMPOUND    LOCOMOTIVES. 

is  accomplished  by  a  steam  pressure  which  is  admitted  at 
one  end  of  the  double  piston  through  a  small  valve  that  is 
actuated  by  a  lever  from  the  cab.  The  steam  enters  the 
small  valve  from  the  h.  p.  steam  pipe  through  a  small  copper 
pipe  connecting  the  two.  The  piston  is  cushioned  at  each 
end  of  the  stroke  by  the  steam  that  is  being  used,  and  no 
dash-pots  are  necessary.  At  starting  the  engineer  moves 
a  lever  in  the  cab  which  admits  steam  back  of  the  piston 
and  closes  the  intercepting  valve  and  opens  the  exhaust 
from  the  h.  p.  cylinder  to  the  atmosphere  for  as  long  a 
period  as  may  be  desired  at  starting. 

The  reducing  valve  is  a  part  of  the  stem  of  the  double 
piston,  thus  no  separate  piece  is  used  for  it.  Drawings 
are  not  obtainable  at  this  writing  on  account  of  patent 
complications, 


CHAPTER  XVIII. 

DESCRIPTION  OF  FOUR-CYLINDER  NON-RECEIVER  COMPOUNDS, 
"CONTINUOUS"  EXPANSION  OR  WOOLF  TYPE.  VAUCLAIN 
AND  NON-RECEIVER  TANDEM  TYPES. 

117.  The  Dunbar  System. — A  four-cylinder  compound 
locomotive  was  built  by  the  Boston  &  Albany  Railroad  Com- 
pany in  1883,   under   the   Dunbar  patents.     The   cylinders 
were  12  inches   and   20   inches   in   diameter,  by   26   inches 
stroke,  and  were   arranged   tandem  with   the  h.  p.  and  1.  p. 
pistons  on  the  same  piston  rod.     The  engine  could  be  worked 
compound  or  non-compound  at  will.     After  working  about 
seven  months  the  locomotive  was  changed  to  a  single  expan- 
sion  engine  as  it  was  apparently  no  more  economical  than 
the  single  expansion  locomotives.     It  is  stated  that  the  ports 
were  too  small  and  that  the  inventor  was  absent  during  the 
trial.      As   the   locomotive  was  an  experiment,  it  is  not  sur- 
prising under  the  circumstances  that  the  results  were  unsatis- 
factory. 

118.  The  Du  Bousquet  ( Woolf)  System  on  the  North- 
ern Railway  of  France. — A  successful  application  of  the 
tandem  form  of  compound  engine  to  a  locomotive  has  been 
made  by  Mr.  G.  Du  Bousquet,  of  the  Northern  Railway  of 
France.     This  locomotive  is  an  eight-coupled  outside  con- 
nected engine,  all  of  the  weight  being  on  the  driving  wheels. 
It  was   originally   a   single   expansion    locomotive,    having 
cylinders   19.68   inches  in   diameter  by  25.59  inches  stroke. 
The  boiler  pressure  of   142.2   pounds,  gauge,  is  the  same  as 
before    converting    it.     The    principal    dimensions   of    this 
locomotive  are  as  follows  : 

211 


212 


COMPOUND    LOCOMOTIVES. 


Diameter  of  high-pressure  cylinders 
"         "  low-pressure 

Stroke  of  pistons 

Diameter  of  driving  wheels 

Total  weight,  all  on  driving  wheels. 

Area  of  grate 

Total  heating  surface 


15  inches. 

26 

25.6    " 

51.2    " 

1 13,970  pounds 

22.4  sq.  ft. 

1,356       "    " 

The  changes  in  the  distribution  and  amount  of  the 
weights  on  the  axles  on  account  of  converting  are  given  as 
follows  : 

Simple.  Compound. 

First  axle 26,900  29,670 

Second  axle 24,470  31,390 

Third  axle 26,670  30,820 

Fourth  axle 20,500  22,090 


Total 98,540 


113,970 


FIG.   108. 
Cylinders  and  Steam  Chest  of  the  Du  Bousquet  Type. 

To  balance  the  increased  weight  of  the  cylinders  a  foot 
board  weighing  6,600  pounds  was  put  in.  Fig.  108  illus- 
trates the  arrangement  of  the  cylinders  and  valve  chest, 
and  is  worthy  of  careful  examination.  It  will  be  seen  that 
the  steam  distribution  for  both  cylinders  is  controlled  by 
one  valve,  the  1.  p.  valve  being,  as  it  were,  inside  of  the 
h.  p.  valve.  The  arrows  clearly  indicate  the  paths  of  the 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    213 

steam.    '  The  principal  dimensions  relating  to  this  valve  gear 
are  as  follows  : 


Travel  of  valve 

Steam  lap,  both  cylinders,  front 
"       "  "  back 

Exhaust  lap,  high-pressure 

"       low  pressure  ...... 


6.22  ins. 
1.34    " 
1.22    " 
o.oo    " 
0.32    " 

Ports,  high-pressure  steam  .........................    17-72  ins.  X  1.38    " 

"      Jow-pressure      "        ..........................    17-72    "     X  1.97    " 

exhaust  ..................    ......    17.72   "     X  3-54    " 

Angular  advance  of  eccentrics  ......................  30    deg. 

Clearance,  per  cent.,  of  cylinder  volume  h.  p  ...........  15.4 

"       "        "         "  "  1-  P  ...........  7-0 

Volume  of  connecting  passages,  per  cent,  of  h.  p.  volume  16.5 

The  features  of  this  design  which  are  specially  note- 
worthy are  that  the  dead  space  between  the  cylinders  is 
reduced  to  a  minimum,  the  h.  p.  clearance  space  is  large, 
and  that  there  are  no  bushings  between  the  cylinders,  but 
instead  there  are  outside  stuffing  boxes  which  are  easily 
accessible. 

119.  Indicator  Cards  from  the  Du  Bousquet  (Woolf) 
Compound.—  The  indicator  cards  shown  by  Figs.  109  to 
113,  inclusive,  illustrate  the  steam  distribution  in  this  loco- 


H45. 


FIG.  109. 
Indicator  Card  at  Slow  Speed,  from  Du  Bousquet  Type. 

motive.  The  effect  of  piston  speed  upon  the  distribution 
is  well  illustrated  by  Figs,  no  and  112,  which  were  taken 
at  the  same  nominal  point  of  cut-off,  but  as  the  two  pairs 


214 


COMPOUND    LOCOMOTIVES. 


of  cards  are  apparently  from  opposite  ends  of  the  cylinders, 
it  is  probable  that  the  great  increase  in  compression  shown 
in  Fig.  112  is  partially  due  to  irregularity  in  the  valve 
motion.  The  mean  pressures  in  these  diagrams  and  the 
percentage  of  the  total  work  done  in  the  h.  p.  cylinder  are 
as  follows  : 


Mean  pressure. 

H.  p.  L.  p. 

Fig.  109 79.36  30.87 

"   no 63.01  21.76 

III 51-20  15.36 

"    112 , 36.84  15.22 

"   113 31-86  9-53 


Per  cent,  of  work 

done  in  h.  p. 

46.2 

49.1 
52-6 

44-7 
52.7 


145, 


Indicator  Card, 


FIG.  no. 

Cut-Off,  Du  Bousquet  Type. 


-(45. 


Indicator  Card, 


FIG.  in. 
Cut-Off,  Du  Bousquet  Type. 


This  locomotive  has  been  carefully  tested  in  comparison 
with  a  single  expansion  locomotive  belonging  to  the  same 
original  class.  The  compound  hauled  trains  about  12  per 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.     2  1  5 

cent,  heavier  than  the  single  expansion  locomotive,  with  a 
noticeable  saving  in  fuel,  while  with  trains  of  the  same 
weight  the  saving  in  fuel,  as  reported  by  Mr.  Du  Bousquet, 
was  from  13.5  to  25.8  per  cent.  The  average  of  five  tests 
is  21.9  per  cent. 


FIG.  112. 
Indicator  Card,  -ffa  Cut-Off,  Medium  Speed,  Du  Bousquet  Type. 


FIG.   113. 
Indicator  Card,  TVu  Cut-Off,  Slow  Speed,  Du  Bousquet  Type. 

120.  Baldwin  Locomotive  Works  (Vauclain)  System. 

—The  first  locomotive  of  this  type  was  built  by  the  Bald- 
win Locomotive  Works  in  the  fall  of  1889,  and  was  put  to 
work  on  the  Philadelphia  Division  of  the  Baltimore  &  Ohio 
Railroad.  The  general  arrangement  of  the  cylinders  and 
valve  is  shown  by  Figs.  114  to  123.  The  method  by  which 
the  power  from  both  cylinders  is  transmitted  through  one 
crosshead  is  shown  in  Figs.  118  and  119,  which  also  shows 


216  COMPOUND    LOCOMOTIVES. 

the  direct  connections  of  the  valve.    The  steam  distributing 


m  * 


FIG.  114. 
Vauclain  Cylinders  with  High-Pressure  Above. 


FIG.  115 
Vauclain  Cylinders  with  Low-Pressure  Above. 

valve    is    a    hollow    piston    valve,  the   action   of   which  is 
illustrated  by  Fig.  120. 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    217 


The  cylinders  are  arranged  two  on  each  side,  with  the 
1.  p.  cylinder  directly  above  or  below  the  h.  p.  cylinder, 
depending  upon  the  service  and  the  clearances  and  conditions 


FIG.  1 1 6. 
Vauclain  Piston  Valve. 


to  be  met.     The  main  valve  chamber,   which    replaces    the 
steam  chest  of   the  ordinary  h.  p.  locomotive,  is  cast  in  one 


FIG.  117. 
Vauclain  Piston  Valve  Bushing. 


piece  with  the  cylinder  casting  and  is  placed  as  near  the 
cylinders  as  possible  in  order  to  give  short  steam  passages. 
The  by-pass,  or  starting  valve,  is  located  below  the 
cylinders  and  main  valve.  This  starting  valve  is  not  con- 
nected in  any  way  with  the  valve  gear  of  the  locomotive, 


218 


COMPOUND    LOCOMOTIVES. 


and  is  operated  from  the  cab  by   a  small  lever  located  near 
the  reverse  lever. 

In  order  to  illustrate  more  clearly  the  passage  of  steam 
through  the  steam  valve  to  and  from  the  cylinders,  the  main 
valve  is  shown  in  Fig.  120  as  being  between  the  cylinders. 
For  the  same  reason  the  starting  valve  is  shown  between  the 
cylinders,  Figs.  121,  122  and  123. 


FIG.  i i 8. 
Arrangement  of  Crosshead,  Guides  and  Piston,  Vauclain  Type. 

In  this  design,  at  the  present  time,  the  air  valve,  shown 
in  Fig.  116,  on  the  end  of  the  piston  valve,  is  no  longer 
used. 

From  Fig.  120  it  is  seen  that  the  steam  valve,  shown 
between  the  cylinders,  is  a  hollow  piston  with  solid  ends. 
A  cavity  extends  around  the  middle  of  the  valve.  The 
passages  and  ports  lettered  A  are  connected  directly  with 
the  steam  pipes  leading  from  the  boiler  to  the  valve  chamber  ; 
those  lettered  B  are  ports  and  passages  leading  from  the 
steam  valve  to  the  h.  p.  cylinder,  and  those  lettered  D  con- 
nect the  steam  valve  with  the  1.  p.  cylinder.  C  is  the  final 
exhaust  passage  to  the  atmosphere. 

With  the  valve,  as  shown  in  Fig.  120,  the  steam,  at  boiler 
pressure,  is  entering  the  valve  chamber  at  the  port  A  on  the 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    2IQ 


left  of  the  figure,  and  as  the  end  of  the  valve  does  not  cover 
the  port  B  on  the  left,  the  steam  passes  from  A  to  B  and  so 
into  the  front  end  of  the  h.  p.  cylinder,  where  it  expands 
during  the  time  the  port  is  closed  by  the  valve. 

At  this  time  in  the  back  end  of  the  h.  p.  cylinder  there 
is  steam  that  has  been  used  in  expansion  and  is  ready  for 
exhausting  into  the  1.  p.  cylinder.  It  now  passes  through 


FIG.  119. 
Vauclain  Crosshead. 

the  passage  B  on  the  right,  to  the  steam  valve  and  to  the 
inside  of  the  valve,  where  it  passes  from  the  back  end  to  the 
front  end  of  the  valve  into  the  passage  D  on  the  left  of  the 
figure,  and  thence  into  the  front  end  of  the  1.  p.  cylinder,  as 
shown  by  the  arrows. 

In  the  back  end  of  the  1.  p.  cylinder  is  steam  that  is 
ready  for  exhausting  into  the  stack.  It  has  been  used  in 
the  1.  p.  cylinder.  It  now  passes  from  the  back  end  of  the 
1.  p.  cylinder  through  the  passage  D,  on  the  right,  to  the 
cavity  around  the  steam  valve,  thence  to  the  exhaust  passage 
and  to  the  atmosphere,  as  shown  by  the  arrows. 


220 


COMPOUND    LOCOMOTIVES. 


FIG.  120. 
Steam  Distribution,  Vauclain  Type. 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    221 

The  simultaneous  action  of  the  steam  in  both  ends  of 
both  cylinders  is  as  follows  :  While  steam  is  entering  the 
front  end  of  the  h.  p.  cylinder  direct  from  the  boiler  past 
the  end  of  the  steam  valve,  the  steam  in  the  back  end  is 
exhausting  through  the  steam  valve  to  the  front  end  of  the 
1.  p.  cylinder,  and  the  steam  from  the  back  end  of  the  1.  p. 
cylinder  is  exhausting  into  the  cavity  around  the  valve,  and 
thence  to  the  exhaust  pipe  and  the  atmosphere.  This  is 
the  course  of  the  steam  in  the  cylinders  when  the  engine  is 
working  compound,  and,  with  the  exception  of  the  small 
jet  of  high  pressure  steam  admitted  through  the  by-pass 
valve,  the  same  course  is  followed  by  the  steam  when  the 
engine  is  working  in  what  is  called  "  high  pressure." 

To  make  as  plain  as  possible  the  course  of  the  steam 
when  the  engine  is  working  with  some  of  the  high  pressure 
steam  in  the  1.  p.  cylinder,  reference  is  made  to  Fig.  120. 
Suppose  a  pipe  to  connect  the  passages  B  B,  and  to  have  a 
valve  in  it  ;  now,  if  the  valve  is  open,  as  it  is  when  the  lever 
in  the  cab  is  in  its  middle  or  front  position,  steam  can  pass 
freely  through  the  valve  and  pipe  from  one  passage  B  to 
the  other  B  and  balance  the  h.  p.  -piston.  Now  this  is 
exactly  what  takes  place  when  the  by -pass  valve  is  used, 
and  it  is  done  as  follows  : 

Steam  passes  from  the  boiler  into  the  steam  valve  cham- 
ber, and  continues  on  into  the  steam  passages  of  the  h.  p. 
cylinder.  A  large  part  of  this  steam  continues  on  to  the 
1.  p.  cylinder,  just  as  when  the  engine  works  compound,  but 
the  remainder  of  the  steam  passes  through  the  pipe  and 
starting  valve  to  the  back  steam  passage  B  on  the  right 
of  Fig.  120,  mingling  with  the  steam  that  is  exhausting  from 
the  back  end  of  the  h.  p.  cylinder,  and  thence  to  the  front 
end  of  the  1.  p.,  thus  increasing  the  pressure  of  steam  on 
the  1.  p.  cylinder.  This  increase  goes  on  until  the  engine 
starts.  After  the  engine  starts  the  pistons  move  so  rapidly 
that  the  small  opening  in  the  by-pass  valve  cannot  supply 


222 


COMPOUND    LOCOMOTIVES. 


steam  fast  enough  to  keep  up  the  pressure.  If  the  engine 
does  not  start  readily  the  pressure  in  the  1.  p.  cylinder  goes 
on  increasing  until  it  reaches  boiler  pressure.  It  will  be 
seen  that  back  pressure  in  the  h.  p.  cylinder  is  increased  by 


FIG.  121. 

Starting  Valve    and  Cylinder    Cocks,  Vauclain    Type. 
Starting  Valve  Open  and  Cylinder  Cocks  Closed. 

this,  and  therefore  the  work  done  in  the  h.  p.  cylinder  is 
less,  under  these  conditions,  than  when  the  engine  is 
working  compound,  but  the  work  done  in  the  1.  p.  cyl- 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    223 

inder  is  much  greater  than  when  working  compound. 
The  piston  in  the  1.  p.  cylinder  being  of  greater  area  than 
that  in  the  h.  p.  cylinder,  the  combined  effort  of  the  two 


FIG.  122. 

Starting  Valve    and    Cylinder  Cocks,  Vauclain    Type. 
Starting  Valve  Closed  and  Cylinder  Cocks  Closed. 

pistons  is  much  greater  when  the  engine  is  working  with 
some  h.  p.  steam  entering  the  1.  p.  cylinder  than  when 
working  compound. 


224 


COMPOUND    LOCOMOTIVES. 


The  steam  passing  through  the  by-pass  valve,  when  the 
engine  is  working  "  high  pressure,"  acts  just  as  a  leak  past 
the  h.  p.  piston  would  act.. 

The  operation  of  the  starting,  or  by-pass   valve,  will   be 


FIG.  123. 

Starting    Valve    and    Cylinder    Cocks,    Vauclain    Type. 
Starting  Valve  Open  and  Cylinder  Cocks  Open. 

understood  by  referring  to  Fig.  121.     On  the  right   of   the 
figure  is  a  small  diagram  showing  the  positions  of  the  lever 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    225 

in  the  cab,  the  full  line  corresponding  to  the  position  of 
the  lever  when  the  valve  bears  the  same  relations  to  the 
ports,  as  shown  in  the  illustration.  It  will  be  seen  that  in 
this  position  of  the  valve,  steam  can  pass  freely  from  one  end 
of  the  h.  p.  cylinder,  through  the  ports,  into  the  inside  of  the 
starting  valve,  and  so  on  to  the  steam  passage  leading  to 
the  other  end  of  the  h.  p.  cylinder.  This  is  the  position  of 
the  valve  when  the  engine  is  working  with  some  of  the 
h.  p.  steam  passing  to  the  1.  p.  cylinder. 

Fig.  122  shows  the  position  of  the  starting  valve  when 
the  engine  is  working  compound,  all  the  ports  being  covered, 
no  steam  is  passing  through  the  valve.  The  full  line  in 
the  diagram  at  the  right  shows  the  position  of  the  lever  in 
the  cab,  the  right  of  the  figure  being  toward  the  back  end 
of  the  engine. 

In  Fig.  123  is  shown  the  position  of  the  valve  and  of 
the  lever  in  the  cab,  when  the  cylinder  cocks  and  starting 
valve  are  open.  In  this  position  there  is  free  communica- 
tion between  both  ends  of  both  cylinders,  and  the  cylinder 
cock  drain  pipe,  through  the  centre  of  the  valve.  This 
allows  the  cylinders  to  be  drained,  as  shown  clearly  by  the 
arrows.  But,  of  course,  the  drain  pipe  is  lower  than  the 
h.  p.  cylinder,  and  not  above  it,  as  is  here  shown  for  the 
purpose  of  giving  a  readily  understood  explanation. 

Figs.  124  to  126  show  a  new  type  of  air  valve  and  cyl- 
inder drain  cock  that  has  just  been  introduced  fpr  this  type 
of  engine.  The  experience  with  it  is  limited  at  this  time, 
but  it  promises  well,  and  is  easily  accessible.  The  body  of 
the  cock  is  in  one  casting,  into  which  are  put  the  two  taper 
plugs,  one  of  which,  X,  Fig.  125,  controls  the  steam  for 
starting,  and  the  other,  Z,  controlling  the  1.  p.  cylinder  cock. 
The  passage  leading  to  the  cock  X  is  connected  to  opposite 
ends  of  the  h.  p.  cylinder,  and  those  from  plug  Z  lead  to 
opposite  ends  of  the  1.  p.  cylinder.  The  two  cocks  have  a 
squared  end  upon  which  is  one  arm  which  operates  the  two 


226 


COMPOUND    LOCOMOTIVES. 


cocks  simultaneously.  In  position  No.  i.  the  plug  X allows 
steam  to  pass  through,  putting  in  communication  the 
opposite  ends  of  h.  p.  cylinder,  thence  through  valve  to 
effective  side  of  1.  p.  piston;  all  the  openings  in  cock  Z 
being  closed.  When  the  arm  is  moved  to  position  No.  2, 


FIG.  124. 
Recent  Form  of  Starting  Valve  and  Cylinder  Cocks,  Vauclain  Type. 

the  opening  in  plug  X  allows  the  steam  to  pass  through  as 
before,  but  it  also  brings  hole  G  opposite  hole  H,  allowing 
any  water  to  escape  from  h.  p.  cylinder  to  atmosphere. 
Plug  Z,  with  arm  in  position  No.  2,  allows  the  three  open- 
ings in  the  plug  to  come  opposite  the  three  openings  in  the 
body,  thus  draining  the  1.  p.  cylinder.  The  arm  in  position 
No.  3  closes  all  openings  and  is  the  running  position.  The 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    227 


r 


FIG.  126. 

Details   of  Recent  Form  of  Starting  Valve 
and  Cylinder  Cocks,  Vauclain  Type. 


226  COMPOUND    LOCOMOTIVES. 

cock  is  operated  from  the  cab  by  a  lever  with  a  notched 
quadrant,  corresponding  to  the  three  positions  of  the  arm. 
The  starting  valve  and  cylinder  cock  is  applied  to  the  cyl- 
inder, as  shown  in  Fig.  124. 

121.  Distribution  of  Pressure  on  Pistons. — The 
feature  of  this  design,  which  at  first  glance  would  seem  to 
be  most  open  to  criticism,  is  the  connection  to  one  cross- 
head  of  two  pistons,  of  which  the  centres  are  about  18 
inches  apart  and  on  which  the  total  pressures  must  differ 
considerably.  To  determine  the  amount  and  variation  of 
this  difference  of  pressure  with  reasonable  exactness  an 
examination  of  a  very  large  number  of  indicator  cards  taken 
simultaneously  from  both  h.  p.  and  1.  p.  cylinders  would  be 
necessary,  and  the  inertia  of  the  reciprocating  parts  must 
be  taken  into  account.  See  Appendix  P.  Some  knowledge 
of  the  subject  can,  however,  be  gained  from  an  examination 
of  the  indicator  diagrams  shown  in  Figs.  1 1  and  12.  The 
data  for  these  diagrams  is  given  in  Table  DD.  The  dia- 
grams were  divided  into  ordinates  as  shown  in  Figs.  127 
and  128,  and  the  difference  between  the  forward  pressure 
on  one  side  of  the  piston  and  the  back  pressure  on  the 
other  side  was  plotted  for  each  ordinate,  allowance  being 
made  for  the  piston  rod  areas.  When  the  starting  valve  is 
opened  these  results  will  be  materially  altered.  The  inertia 
of  the  reciprocating  parts  was  calculated  for  the  different 
points  of  the  stroke.  See  Appendix  P. 

From  these  results  the  curves  shown  by  the  heavy  full 
lines  in  Figs.  127  and  128  were  plotted.  These  curves 
indicate  very  closely  the  actual  pressures  on  the  crosshead, 
where  the  piston  rods  are  attached  for  the  h.  p.  and  1.  p. 
cylinders,  at  different  parts  of  the  stroke,  the  inertia  of  the 
reciprocating  parts  being  taken  into  account.  The  num- 
bers on  the  diagrams  refer  to  the  correspondingly  numbered 
indicator  cards  of  Figs.  1 1  and  12. 

The  full  line  on  Figs.  127  and  128  shows  the  difference 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.     22Q 


TABLE  D  D. 

Giving  Data  for  Indicator  Cards  showing  Steam  Distribution  on    Baldwin 
Compound,  on   C.  M.   &=  St.  P.  Railway.     See  Figs.  127  and  128. 


Card 

1    -"" 

•L« 

Miles 

Cut-off  in 
Inches. 

Mean  Effective 
Pressure. 

tjj  gu 

Horse-Power. 

?fe 

No. 

<u  s  « 

IsJ 

per 

W  5(2^ 

u^a*' 

i"0 

Hour. 

H.  P. 

L.  P. 

H.  P. 

L.P. 

llS-B 

H.  P. 

L.  P. 

£|J 

F     i 

i76 

256 

47.10 

12.25 

15.06 

37-50 

13-75 

40.43 

142.4 

145-2 

5°. 

B        2 

176 

256 

47.10 

12.25 

15.00 

41.25 

12.50 

34-75 

141.4 

127.3 

47- 

F     3 

170 

228 

41-95 

12.25 

15.06 

40.00 

15.00 

44.10 

I35.3 

141.1 

51- 

B     4 

170 

244 

44.90 

13-25 

15-94 

51.88 

15.00 

41.70 

169.4 

145.6 

46. 

F     5 

168 

232 

42.69 

13.28 

15.90 

47-50 

20.00 

58.80 

162.9 

191-3 

54- 

F    6 

174 

140 

25.76 

13.28 

15.90 

64.50 

25.00 

73-50 

134.0 

144-5 

52- 

B     7 

177 

1  88 

34-59 

14-25 

16.87 

68.75 

22.50 

62.55 

i73-o 

168.3 

49- 

F    8 

192 

35-33 

17.62 

70.00 

28.75 

84.52 

199.7 

227.7 

53- 

B     9 

177 

172 

3I-65 

15-44 

17-75 

75-00 

25.00 

69.50 

172.7 

171.1 

B  10 

171 

156 

28.70 

15-44 

17-75 

78.75 

27.50 

76.45 

164.4 

170.7 

Si- 

F  n 

T75 

120 

22.08 

17-63 

82.50 

37-50 

110.25 

146.9 

175-6 

34- 

F    12 

170 

80 

14.72 

15.41 

17-63 

81.25 

38.75 

ii3-93 

96-4 

127.8 

57- 

B  13 

176 

48 

8.83 

21.26 

22.75 

116.25 

46.25 

128.56 

74-7 

88.3 

54- 

between  the  actual  pressure  on  the  crosshead  due  to  the 
h.  p.  piston,  and  that  due  to  the  1.  p.  piston.  The  vertical 
distances  above  the  neutral  line  A  A  to  the  full  curved  line 
represent  the  excess  of  the  total  pressure  on  the  h.  p.  piston 
above  that  on  the  1.  p.  piston.  Distances  below  this  line 
indicate  how  much  the  total  pressure  .upon  the  1.  p.  piston 
exceeds  that  on  the  h.  p.  piston.  The  scale  of  pressures  is 
given  on  the  side  of  the  diagram.  It  will  be  seen  that  the 
greatest  difference  in  pressure  is  for  the  diagram  taken  at 
slow  speed  and  late  cut-off,  and  that  for  high  speed  and  early 
cut-off  the  difference  is  comparatively  small.  Also  that  the 
effect  of  higher  speed  and  lower  initial  pressure  with  the 
same  cut-off  is  to  greatly  change  the  amount  and  distribu- 
tion of  the  excess  pressure.  The  tendency  is  to  tip  the 
crosshead,  and  hence  to  bring  a  bending  load  on  the  piston 
rods.  It  does  not  follow  that  this  fact  is  an  argument 
against  the  adoption  of  this  design,  but  simply  that  a  vary- 
ing load,  acting  with  a  leverage  of  about  18  inches,  and 
having  from  300  to  600  reversals  per  minute  at  ordinary 
speeds,  should  be  provided  for  in  addition  to  the  usual 
stresses  on  piston  rods. 

The    lines    on    diagrams,    Figs.    127  and    128  have  the 
following    signification  :    The  dotted    lines  show   the  total 


230 


COMPOUND    LOCOMOTIVES. 


steam    pressures  on  the  pistons  of  the  h.  p.  and  1.  p. 
ders,    deducting   the    back    pressure.      The    h.   p. 
pressures  are  laid  out  above  the  line  AA  and  the  1.  p. 


cylin- 
piston 
piston 


FIG.  127. 

Diagrams  showing  Total  Steam  Pressure  on  High  and  Low-Pressure 
Pistons  at  Different  Points  in  the  Stroke  in  a  Vauclain  Compound.  Also 
showing  the  Inertia  of  the  Pistons  and  Piston  Rods  and  the  Total  Comparative 
Pressures  on  the  Top  and  Bottom  of  the  Crosshead,  Taking  into  Account  the 
Inertia  of  the  Pistons  and  Piston  Rods. 

The  Scale  at  Side  of  Diagram  is  in  Thousands  of  Pounds. 

pressures  are  laid  out  below  the  line  AA.  The  forward 
stroke  leads  from  left  to  right  and  the  back  stroke  from 
right  to  left.  The  straight  dotted  lines  represent  the  inertia 
of  the  piston  and  piston  rod  and  do  not  include  the  inertia  of 
the  crosshead  and  main  rod.  The  full  fine  lines  represent 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    231 

the  combined  effect  of  the  steam  pressure  and  inertia  of  the 
piston  and  rod.  The  heavy  full  lines  represent  the  differ- 
ence between  the  pressures  on  the  h.  p.  and  1.  p.  pistons  at 


FIG.  128. 

Diagrams  showing  Total  Steam  Pressure  on  High  and  Low-Pressure 
Pistons  at  Different  Points  in  the  Stroke  of  a  Vauclain  Compound.  Also 
showing  the  Inertia  of  the  Pistons  and  Piston  Rods  and  the  Total  Comparative 
Pressures  on  the  Top  and  Bottom  of  the  Crosshead,  Taking  into  Account  the 
Inertia  of  the  Pistons  and  Piston  Rods. 

The  Scale  at  Side  of  Diagram  is  in  Thousands  of  Pounds. 

the  crossheads.  The  scale  at  the  side  of  the  diagram 
indicates  the  total  difference  in  pressure,  and  shows  the 
amount  of  the  twisting  tendency  on  the  crosshead  for  the 
different  parts  of  the  stroke  and  under  different  conditions. 


232  COMPOUND    LOCOMOTIVES. 

The  indicator  cards  from  which  these  diagrams  were  taken 
are  from  a  ten-wheel  Vauclain  compound  on  the  Chicago, 
Milwaukee  &  St.  Paul  Railroad,  and  the  data  regarding  the 
cards  is  given  in  Table  D  D,  the  cards  themselves  are  given 
by  Figs.  1 1  and  12. 

122.  Advantages  Claimed  for  the  Baldwin  Loco- 
motive Works  (Vauclain)  System. —  The  claims  made 
by  the  Baldwin  Locomotive  Works  for  the  Vauclain  com- 
pound, after  an  experience  with  about  400  engines,  working 
under  a  great  variety  of  conditions,  are  as  follows. 

These  claims  represent  what  this  system  of  compound 
has  been  designed  to  accomplish  : 

1.  To  compound  an  ordinary  locomotive  with  the  fewest  possible  alterations  nec- 
essary to  obtain  the  greatest  efficiency  as  a  compound  locomotive. 

2.  To  develop  the  same  amount  of  power  on  each  side  of  the  locomotive,  and 
avoid  the  racking  of  the  machinery  resulting  from  uneven  distribution  of  power. 

3.  To  make  a  locomotive  in  every  respect  as  efficient  as  a  single  expansion  engine 
of  similar  weight  and  type. 

4.  To  insure  the  least  possible  difference  in  the  cost  of  repairs. 

5.  To  attain  the  utmost  simplicity  and  freedom  from  complication. 

6.  To  realize  the  maximum  economy  of  fuel  and  water. 

7.  To  require  the  least  possible  departure  from  the  methods  of  handling  usual 
with  single  expansion  locomotives. 

8.  To  permit  a  train,  in  case  of  break-down,  to  be  brought  in  without  unusual 
delay,  when  using  but  one  side  of  the  locomotive. 

9.  To  be  equally  applicable  to  passenger  or  freight  engines. 

10.  To  withstand  the  rough  usage  incidental  to  ordinary  railroad  service. 

There  are  some  who  have  had  experience  with  this  type 
of  compound  who  would  not  certify  to  the  justice  of  these 
claims,  but  the  great  majority  of  those  who  are  using 
these  engines  believe  that  the  Baldwin  Locomotive  Works 
have  accomplished  what  they  set  out  to  do.  It  is  notice- 
able that  the  claim  is  made  that  the  engines  are  equally 
applicable  for  passenger  and  freight  engines.  As  this  is  not 
true  of  any  compound  in  existence,  and  cannot  be,  from  the 
nature  of  things,  it  is  not  true  for  this  type.  So  far  as  the 
mechanical  construction  is  concerned,  the  statement  is  true ; 
but  in  the  matter  of  efficiency,  it  cannot  be  true,  for  no 
compound  which  has  as  much  compression  and  wire-drawing 
as  this,  and  other  types  at  high  speeds,  can  ever  be  rela- 


FOUR-CYLINDER  NON-RECEIVER  TANDEM  TYPES.    233 

tively    so    efficient,    in    comparison   with    single    expansion 
engines,  in  passenger,  as  in  freight  service. 

123.  The  Johnstone  System  on  the  Mexican  Central 
Railway. — Figs.  129  and  130  show  the  construction  of  the 
Johnstone  compound  cylinder.  The  h.  p.  piston  is  in  the 
centre  of  the  annular  1.  p.  piston  which  surrounds*it.  Between 
the  pistons  there  is  a  double  barrel  made  of  cast  iron.  One 
of  these  barrels  forms  the  h.  p.  cylinder ;  and  the  other,  the 
outer  one,  forms  the  inner  surface  of  the  annular  1.  p.  piston. 
The  construction  is  clearly  shown  by  the  illustration.  The 
ratio  of  the  cylinders  is  generally  3  to  i.  The  valve,  while 


FIG.  129. 
Cross-Section  Through  Johnstone  Cylinders. 

double,  has  but  one  valve  stem.  It  is  actuated  by  a  link 
motion  as  usual.  The  outer  section  of  the  valve  distributes 
steam  to  the  h.  p.  cylinder,  and  the  inner  section  to  the 
1.  p.  cylinder.  The  inner  section  is  loose  within  the  outer 
section,  and  has  a  motion  of  about  I  inch  independent  of 
the  outer  section,  for  the  purpose  of  giving  a  later  cut-off  in 
the  1.  p.  cylinder,  and  to  reduce  the  compression  in  the 
h.  p.  cylinder.  The  valve  is  cushioned  from  knocking  by 
means  of  two  springs,  one  on  each  side  of  the  inner  valve. 
The  cut-off  obtained  by  this  arrangement  is  given  in  Table 
U  I.  The  starting  valve  used  with  this  system  is  simply  a 
three-way  cock  in  the  cab  having  a  small  pipe  leading  to 
the  steam  chest.  Thirteen  of  these  compounds  are  now 
in  operation.  The  only  change  of  any  importance  that  has 


234  COMPOUND    LOCOMOTIVES. 

been  made  in  the  recent  designs,  is  an  increase  of  the  steam 


FIG.  130. 
Arrangement  of  Johnstone  Cylinders  and  Crosshead. 

port  which  was  done  to  reduce  the  wire-drawing  and  com- 
pression. 


CHAPTER  XIX. 

DESCRIPTION     OF     FOUR-CYLINDER,    TWO-CRANK     RECEIVER 
COMPOUNDS— TANDEM  RECEIVER  TYPES. 

124.  Tandem  Compounds  on  the  Hungarian  State 
Railway. — The  Hungarian  State  railways  have  constructed 
some  tandem  four-cylinder  receiver  compounds  with  two 
cranks  with  the  general  construction  shown  in  Figs.  131, 132 
and  133.  The  general  description  of  these  engines  is  given 
in  Table  C  C,  Appendix  R. 

The  service  is  that  of  hauling  160  tons  at  50  miles  an 
hour  on  a  level.  This  is  practically  passenger  work ;  in 
fact,  this  engine  is  used  in  passenger  traffic.  Like  other 
receiver  compounds  with  two  cranks,  the  indicator  cards 
have  the  same  general  appearance  as  those  taken  from 
two-cylinder  receiver  compounds.  Such  indicator  cards  as 
have  been  given  to  the  public  were  taken  at  slow  speeds. 
These  give  no  indication  of  the  amount  of  compression  in 
the  engines  at  high  speed.  Both  h.  p.  cylinders  exhaust  in 
the  same  receiver.  In  starting,  live  steam  is  admitted  to 
the  1.  p.  cylinders  and  receiver  by  means  of  a  starting  valve 
which  is  opened  by  the  reverse  lever  when  in  full  forward 
gear.  In  this  engine  both  valves  are  connected  to  the  same 
valve  stem,  as  in  the  Mallet  system  used  on  the  Southwest- 
ern railways  of  Russia,  125.  Likewise,  as  in  the  Mallet 
and  Du  Bousquet,  118,  systems,  the  piston  rod  stuffing- 
boxes  are  packed  separately  and  are  accessible  from  the 
outside  as  distinguished  from  the  Brooks  tandem,  127. 
By  connecting  the  two  valves  to  one  stem,  it  is  necessary 
to  raise  the  h.  p.  valve  seat  somewhat,  as  is  clear  from 
Fig.  131,  but  this  does  not  give  a  larger  clearance  to  the 

235 


236 


COMPOUND    LOCOMOTIVES. 


h.  p.  cylinder  than  is  common  in  compound  locomotives. 
In  order  to  reduce  the  weight  of  reciprocating  parts  as 
much  as  possible,  the  h.  p.  piston  is  forged  on  to  the 


FIG.  131. 
Tandem  on  Hungarian  State  Railways — Longitudinal  Section. 


FIG.  132.  FIG.  133. 

Tandem  on  Hungarian  State  Railways — Cross  Section. 

piston    rod,    as    shown    in    Fig.    131.     The  1  .  p.   piston    is 
keyed  on,  as  shown.     The  valve  chest  and  valve  seats  are 


FOUR-CYLINDER  TANDEM  TYPES. 


^37 


inclined,  as  shown  in  Figs,  132  and  133.  In  the  Mallet 
construction  and  the  Brooks  tandem,  the  1.  p.  cylinder  is 
next  to  the  crank,  while  in  this  engine  and  the  tandems 
used  on  the  Northern  Railways  of  France,  the  h.  p.  cylinder 
is  next  to  the  crank.  In  the  Hungarian  type,  the  cylinders 
are  cast  in  one  piece. 

125.  Tandem  Compounds  on  the  Southwestern 
Railways  of  Russia.  — In  this  system  the  1.  p.  cylinder  is 
placed  next  to  the  crank.  Both  valves  are  connected  to 
the  same  valve  stem,  but  are  independently  connected,  as 
shown  in  Fig.  134.  The  1.  p.  piston  is  attached  to  the  piston 


FIG.   134. 
Mallet  Tandem  on' Southwestern  Railways  of  Russia — Longitudinal  Section. 


FIG.  135. 
Piston  for  Mallet  Tandem. 


rod   by  screw-thread  and   pin,  as  shown  in  Fig.  135.     The 
stuffing-boxes  are  accessible  from  the  outside.     The  clear- 


COMPOUND    LOCOMOTIVES. 

ance  in  this  design  is  considerable,  as  the  valve  seats  are 
unusually  high.  The  reciprocating  parts  have  been  made 
light  in  weight  by  the  use  of  single  plate  pistons.  The 
Mallet  starting  gear  is  used,  but  not  of  the  type  that  is 
used  for  two-cylinder  engines.  This  system  has  a  simple 
valve  which  admits  steam  to  the  1.  p.  cylinder  and  receiver 
at  starting  whenever  the  reverse  lever  is  in  full  forward 
gear.  The  construction  of  this  engine  in  the  cylinder  part 
is  clearly  shown  in  Figs.  134  and  135.  The  general  dimen- 
sions are  given  in  Table  C  C,  Appendix  R. 


FIG.  136. 
Indicator  Cards  from  Mallet   Tandem  on  Southwestern  Railways  of  Russia. 

126.  Indicator  Cards  from  Tandem  Compounds  on 
the  Southwestern  Railways  of  Russia. — Some  indi- 
cator cards  taken  at  a  comparatively  slow  speed  are  given 


FOUR-CYLINDER  TANDEM  TYPES. 


239 


in  Fig.  136,  and  the   data  about  the   card  will  be  found  in 
Table  E  E. 

TABLE    EE. 

Giving  data  for  Figs.  134,  135  and  136  for  Mallet  Compound  on  South- 
western Railways  of  Russia.  Cylinders  13  in.  and  rq.?  X  23.6  in.  Drivers 
79  in.  diameter. 


Card 

Number. 

Boiler 
Pressure. 
'.Pounds. 

Revolutions 
Minute. 

I 

162 

79 

2 

I6I.3 

120 

3 

165. 

101 

4 

165. 

1  68 

127.  The  Brooks  Tandem  System. — Figs.  137  to  144 
show  the  details  of  the  tandem  four-cylinder  compound 
recently  brought  out  by  the  Brooks  Locomotive  Works  of 
Dunkirk,  New  York.  The  general  dimensions  of  the  engine 
are  given  in  Table  C  C.  Fig.  137  shows  the  end  view  and 
half  section  through  the  1.  p.  cylinder,  also  shows  the  reduc- 
ing valve  which  admits  steam  from  the  steam  pipe  directly 
to  the  1.  p.  cylinder  at  starting.  Fig.  138  shows  a  section 
through  the  cylinders  longitudinally.  The  h.  p.  cylinder  is 
placed  ahead  of  the  1.  p.  The  1.  p.  valve  is  of  the  ordinary 
pattern  plain  slide  valve.  The  h.  p.  valve  is  of  the  piston 
type.  These  valves  have  an  opposite  motion ;  that  is,  when 
the  h.  p.  valve  goes  ahead  the  1.  p.  valve  goes  back.  This 
reversed  motion  is  produced  by  means  of  the  rocker  arm 
shown  in  Figs.  138  to  140.  The  h.  p.  steam  pipe  has  a  2 
inch  vacuum  valve  and  the  1.  p.  cylinder  has  a  2  inch  relief 
valve.  The  h.  p.  valve  seat  is  made  in  the  form  of  a  bush- 
ing shown  in  Figs.  141  and  142.  The  rock  arm  bearing  for 
reversing  the  motion  of  the  valve  is  oiled  by  means  of  a 
hole  drilled  through  the  centre  of  the  bearing,  as  shown  in 
Fig.  140. 


240 


COMPOUND    LOCOMOTIVES. 


FOUR-CYLINDER    TANDEM    TYPES. 


241 


The  exhaust  steam  from  the  front  end  of  the  h.  p.  cyl- 
inder reaches  the  receiver  through  the  centre  of  the  h.  p. 


FIG.  138. 
Brooks  Tandem — Longitudinal  Section. 


FIG.    139. 
Brooks  Tandem — Plan  of  Steam  Chest. 

-valve,  as  is  evident  from  Figs.  138  and  139.  This  hollow 
h.  p.  valve  has  a  lining  of  wrought  iron  pipe,  as  shown  ; 
the  space  between  the  pipe  and  the  valve  being  filled  with 
;asbestos.  This  valve  has  removable  ends  to  facilitate  the 
insertion  of  packing  rings. 


242 


COMPOUND    LOCOMOTIVES. 


Figs.  143  and  144  show  the  starting  valve  arrange- 
ment. This  valve  has  a  spring  which  keeps  it  closed  under 
normal  conditions,  as  shown  in  Fig.  143,  but  whenever  the 


FIG.  140. 
Brooks  Tandem,  Valve  Rod  Rocker. 


TOH.P.CYL. 


H.P.ST£AM 

IINDUCTION 

PORT. 


TOH.P.CYL, 


P^IG.    141.  FIG.  142. 

Brooks  Tandem.     High-Pressure  Valve  Bushing. 

valve  motion  is  thrown  into  full  forward  or  backward  gear, 
the  projections  on  the  rod  connected  to  the  reverse  shaft 
arm  force  the  spring  down  and  the  valve  open,  as  shown  in 
Fig.  144.  In  this  way  steam  is  admitted  to  the  1.  p.  cyl- 


•   FOUR-CYLINDER    TANDEM    TYPES.  243 

inder  direct   only  when  the  reverse  lever  is  in  full  forward 


FIG.  143. 
Brooks  Tandem — Starting  Valve  Connections. 


FIG.  144. 
Brooks  Tandem — Starting  Valve. 

or  back  gear.     The  connections  for  the  valve  and  the  com- 
bined stuffing-box  are  shown  in  Figs.  138  and  139. 


CHAPTER  XX. 

DESCRIPTION  OF  THREE  AND  FOUR-CRANK  COMPOUNDS. 

A  discussion  of  the  elementary  features  of  these  types 
of  compounds  will  be  found  in  Appendixes  I  and  K. 

128.  Webb  System  ;  Express  Locomotives  without 
Parallel  Rods. — The  general  arrangement  of  the  cylinders 
and  steam  connections  of  compound  locomotives  of  the 
Webb  system  is  illustrated  by  Fig.  145.-  In  this  figure  h  h 


FIG.  145. 
Webb  Three -Cylinder  Compound — Cross  Section  Through  Cylinders. 

are  the  h.  p.  cylinders,  which  are  placed  so  that  the  centres 
are  in  a  transverse  line  about  four  feet  back  of  the   front 

244 


THREE    AND    FOUR-CRANK    COMPOUNDS.  245 

tube  sheet,  and  which  are  connected  to  the  second  pair 
of  driving  wheels.  The  1.  p.  cylinder  /  is  placed  beneath 
the  smoke  box,  and  is  connected  to  the  forward  pair  of 
driving  wheels.  The  course  of  the  steam  from  the  boiler  is 
through  the  pipes  A  A  to  B  B,  and  thence  back  to  the 
h.  p.  cylinders.  The  exhaust  from  these  cylinders  is  led 
through  the  pipes  D  D,  and  thence  around  the  smoke  box 
through  the  two  pipes  C  to  the  1.  p.  steam  chest.  The 
course  of  the  exhaust  from  the  1.  p.  cylinder  is  clearly  in- 
dicated in  the  figure.  The  disposition  of  the  cylinders  and 
steam  pipes  is  essentially  the  same  in  the  Webb  compounds 
for  passenger  and  freight  service.  The  most  noticeable 
peculiarity  of  the  system  is  the  absence  of  driving  connec- 
tion between  the  h.  p.  and  1.  p.  axles,  there  being  no  coup- 
ling rods  on  engines  having  two  pairs  of  driving  wheels. 

129.  Webb     System ;    Freight    Locomotives    with 
Parallel  Rods. — In  one  design  for  freight  service  there  are 
three  driving  axles,  the  first  being  driven  by  the   1.  p.   cyl- 
inder, and  the  second  and  third,  which  are   coupled,  being 
driven  by  the  h.  p.  cylinders.      It  will  be  seen  that  even  in 
this  case  there  is  no  connection   by  coupling  rods   between 
the  h.  p.  and  1.  p.  cylinders.     The  principal  dimensions  of  a 
recent   Webb  compound   locomotive  are  as  given  in  Table 
C  C,  Appendix  R. 

130.  Webb  System    on  Pennsylvania  Railroad. — A 
compound  locomotive  of  this  type  was   purchased  by    the 
Pennsylvania  Railroad  and  put  into  service  in    1889.     The 
results  of  practical  trial  with  the   heavy  trains   used   in  the 
United   States   were   satisfactory  in  economy,   but    unsatis- 
factory in  hauling  power.      It  has   been    found    difficult   to 
start  the  ordinary  weight  of  train  with  this  engine,  owing  to 
the  slipping  of  the  drivers,   which  were   not   provided   with 
parallel  rods.     When  the  trains  are  light  the   engine  works 
with    the    most   excellent   economy,    and   shows  a  decided 
saving  in   fuel.     The  reports   from   the    London   &    North- 


246 


COMPOUND    LOCOMOTIVES. 


western  Railroad  of  England,    where  these    engines    have 
been  principally  used,  are  very  complimentary. 

131.  Three-Cylinder  System  Used  on  the  Northern 
Railways  of  France. — A  compound  locomotive  having  one 
h.  p.  cylinder  and  two  1.  p.  cylinders  was  built  by  the 
Northern  Railway  of  France,  and  exhibited  at  the  Paris 
Exposition  in  1889.  The  general  arrangement  of  the  cyl- 
inders and  steam  connections  of  this  locomotive  is  shown 
in  Fig.  146.  Referring  to  this  figure,  h  is  the  h.  p.  cylinder  ; 
/  /  are  the  1.  p.  cylinders ;  A  is  main  steam  pipe  to  the  h.  p. 


FIG.  146. 

Three-Cylinder  Compound  on  Northern  Railways  of  France. 

cylinder  ;  C  C  is  the  receiver  ;  and  D  D  are  the  1.  p.  exhaust 
pipes.  The  1.  p.  cylinders  are  placed  as  usual,  and  have 
the  valve  chests  above.  The  h.  p.  cylinder  is  placed  below 
the  smoke  box  with  its  valve  chest  B  below  it,  and  is 
inclined  to  an  angle  of  one  in  ten.  The  locomotive  is  of 
the  Mogul  type,  having  six  coupled  driving  wheels,  the 
middle  axle  being  the  main  driving  axle  for  all  three  cyl- 
inders. The  1.  p.  cranks  are  at  right  angles,  and  the  h.  p. 


THREE    AND    FOUR-CRANK    COMPOUNDS.  247 

crank  is  midway  between  them,  thus  making  an  angle  of 
135  degrees  with  each  1.  p.  crank.  It  will  be  noticed  that 
the  receiver  is  formed  in  the  cylinder  castings,  and  not  by 
pipes,  as  in  the  locomotives  previously  illustrated. 

132.  Valve  Gear  for  Three- Cylinder  Compound  on 
Northern  Railways  of  France. — The  h.  p.  valves  are  a 
special  feature  of  this  engine.  These  consist  of  a  main 
valve  and  a  cut-off  valve,  which  slides  on  the  back  of,  or 
below,  the  main  valve,  the  .whole  forming  a  combination 
which  in  principle  is  the  same  as  the  Meyer  and  Ryder  cut- 
offs, The  edges  of  the  cut-off  valve  form  an  oblique  angle 
with  the  axis  of  the  cylinder,  as  in  the  Ryder  valve  gear, 
and  the  ports  in  the  main  valve  are  correspondingly 
inclined  at  the  back  of  that  valve,  but  are  twisted  so  that 
on  the  face  next  to  the  cylinder  they  are  placed  as  is 
customary.  The  edges  of  the  exhaust  port  in  the  cylinder 
casting  are,  however,  inclined,  and  the  exhaust  cavity  in 
the  main  valve  is  formed  to  correspond.  The  yoke  which 
drives  the  main  valve  does  not  fit  it  at  the  sides,  and  so 
permits  a  transverse  movement  while  controlling  it  long- 
itudinally. A  second  yoke  incloses  the  valve,  and  per- 
mits a  longitudinal  movement,  but  holds  it  transversely. 
This  yoke  is  connected  to  a  stem,  which  passes  through 
a  stuffing-box  in  the  side  of  the  valve  chest,  and  is  operated 
from  the  cab  by  lever  connections.  It  is  clear  that  the 
h.  p.  cut-off  can  be  adjusted  at  any  time  by  means  of  this 
connection,  while  the  valve  is  so  proportioned  that  in  its 
extreme  position  the  steam  and  exhaust  ports  remain  open 
for  all  positions  of  the  h.  p.  piston,  and  steam  is  thus 
allowed  to  blow  through  the  h  p.  cylinder  without  doing 
work.  The  engine  can,  therefore,  be  started  by  the  1.  p. 
cylinders  with  steam  from  the  boiler,  the  h.  p.  piston  being 
then  practically  inoperative  ;  and  as  the  1.  p.  cranks  are  at 
right  angles,  the  starting  conditions  will  be  the  same  as 
for  a  single  expansion  locomotive. 


248  COMPOUND    LOCOMOTIVES. 

133.  Summary  of  Three  and  Four-Crank  Com- 
pounds.— It  has  been  shown  by  a  large  number  of  examples 
that  the  four- cylinder  two-crank  types  can  be  made 
perfectly  practicable  in  regular  service  and  with  outside 
connections,  and  for  this  and  other  reasons  it  is  evident 
that  three  or  four-cylinder  compounds  with  more  than  two 
cranks  will  never  be  generally  used,  and,  therefore,  a  con- 
sideration of  the  theoretical  economies  of  such  engines  has 
been  omitted  here.  In  Appendixes  I  and  K  will  be  found 
a  discussion  of  some  features  of  such  three-cylinder  three- 
crank  and  four-cylinder  four-crank  compounds  as  have 
been  built  up  to  this  time. 

Such  other  three  and  four-cylinder  compounds  with 
three  or  four  cranks  as  have  been  designed  have  not  been 
raised  to  sufficient  prominence  to  make  it  desirable  to 
discuss  them  here. 

134  Miscellaneous  Designs  of  Compounds  that 
have  not  been  Put  in  Service. — Besides  the  designs 
already  shown,  a  great  many  have  been  proposed,  such  as 
the  Strong,  Wright,  Ball,  Weir,  and  others  ;  but  as  these 
engines  are  more  or  less  complicated  (some  of  them  are 
exceedingly  complex),  and  have  never  been  put  into 
practical  operation,  their  consideration  is  omitted  here  for 
lack  of  space,  and  also  because  the  practical  value,  whether 
good  or  bad,  of  such  designs  has  not  been  demonstrated 
by  actual  construction. 


CHAPTER  XXI 

SUMMARY   ABOUT   STARTING   GEARS, 

135.  Automatic  Starting  Gears  with  Intercepting- 
Valves. — These  gears  are  used  solely  with  two-cylinder 
receiver  compounds,  and  have  been  described  in  Chapter 
XV.  The  starting  power  with  these  gears  is  at  a  maximum 
at  some  point  during  the  first  revolution.  This  maximum 
point  may  even  occur  during  the  first  quarter,  and  there- 
after the  starting  power  decreases  until  it  becomes  the  same 
as  when  the  engine  is  compounded.  That  is,  the  re'ceiver 
becomes  so  charged  with  exhaust  steam  from  the  h.  p. 
cylinder  that  the  automatic  intercepting  valve  opens  and 
the  engine  works  compound  almost  immediately  after  start- 
ing. This  change  may  take  place  any  time  after  the  first 
exhaust  from  the  h.  p.  cylinder.  If  the  receiver  is  large, 
say  four  times  the  volume  of  the  h.  p,  cylinder,  the  change 
to  compound  may  not  take  place  until  two  or  possibly  three 
exhausts  have  been  made,  but,  ordinarily,  it  will  take  place 
about  at  the  end  of  the  first  half  revolution.  After  this  the 
engine  works  compound,  and  with  a  greatly  reduced  hauling 
power.  It  is  clear  that  the  larger  the  receiver  the  greater 
will  be  the  number  of  exhausts  required  to  fill  it,  so  that, 
with  large  receivers,  the  period  of  increased  starting  power 
will  be  prolonged.  Such  engines  as  have  been  built  with 
these  gears  have  worked  well  in  practice  when  they  were' 
well  designed,  except  in  such  cases  as  have  required  a  long 
continued  heavy  pull  at  starting.  Under  these  conditions, 
this  type  of  starting  gear  has  proved  inadequate.  For 

249 


25O  COMPOUND    LOCOMOTIVES. 

pulling  long  trains  out  of  a  siding,  or  hauling  heavy  loads 
up  a  hill,  or  starting  on  a  hill,  or  for  starting  heavy  close- 
coupled  vestibule  trains,  this  type  of  gear  is  unsatisfactory  ; 
but  for  all  average  work  it  has  been  shown  to  be  quite 
practicable.  As  might  be  supposed,  from  the  development 
of  other  features  of  locomotives,  it  is  the  unusual  condition, 
not  the  average,  which  controls,  and,  therefore,  in  starting 
gears  for  compounds  it  has  been  found  necessary  to  take 
into  account  the  maximum  and  unusual  requirements  rather 
than  the  average.  Perhaps  it  is  for  this  reason  that  recent 
designs  of  starting  apparatus  of  this  class  —  automatic 
intercepting  valves — have  been  given  an  "emergency" 
feature  which  permits  the  engineer  to  run  with  a  separate 
exhaust  for  the  h.  p.  cylinder  when  it  is  found  desirable  to 
do  so,  to  save  time  or  to  haul  a  few  additional  cars  over  a 
bad  place.  The  Richmond  Locomotive  Works  (Mellin) 
gear  is  an  example  of  this  kind. 

From  recent  developments  it  is  quite  clear  that  there  is 
now  a  tendency,  even  with  those  who  formerly  favored 
automatic  gears,  to  give  the  engineer  such  apparatus  as  will 
enable  him  to  run  non-compound  when  starting  at  slow 
speeds  for  a  sufficient  time  to  enable  him  to  get  control  of 
the  train.  Mr.  von  Borries,  who  has  been  a  strong  advocate 
of  automatic  starting  gear  of  the  kind  that  permits  only  one 
revolution  at  the  most  before  automatically  changing  to 
compound  action,  has  quite  recently  decided  to  use  a  new 
arrangement,  on  all  future  compounds,  which  will  permit  the 
engine  to  be  run  non-compound  a  sufficient  length  of  time 
to  enable  the  engineer  to  get  control  of  the  train.  This  is 
especially  important  by  reason  of  the  wide  experience  of 
Mr.  von  "Borries  with  two-cylinder  receiver  compound  loco- 
motives, and  from  the  fact  that  he  was  the  original  inventor 
of  the  automatic  intercepting  valve. 

From  what  is  now  before  us,  it  appears  that  Mr.  Mallet's 
original  plan  of  placing  the  compound  and  non-compound 


SUMMARY    ABOUT    STARTING    GEARS.  251 

action  at  the  will  of  the  engineer  is  coming  to  the  front  for 
future  use.  At  the  first  introduction  of  compounds,  railroad 
men  feared  to  give  engineers  control  of  the  compound 
action,  and  therefore  favored  automatic  intercepting  valves  ; 
and  also  it  was  not  thought  advisable  to  give  the  engineer 
any  more  handles  to  turn  or  duties  to  perform  than  he 
already  had  ;  but  now  that  all  are  more  familiar  with  com- 
pounds, and  the  advantages  of  compounding  are  better 
appreciated,  there  is  a  general  tendency  to  make  engines 
satisfactory  at  starting  and  at  all  other  times,  even  with  the 
probability  of  requiring  engineers  to  exercise  better  judg- 
ment and  to  do  more  manual  labor  when  starting  out  with 
a  heavy  load.  This  seems  a  very  logical  conclusion,  and 
will  probably  lead  to  simpler  designs  hereafter,  and  further, 
this  will  give  a  two-cylinder  receiver  compound  that  will 
start  trains  with  quite  as  good  satisfaction  as  the  four- 
cylinder  non-receiver  type,  and  generally  better  than  the 
single  expansion  locomotive.  Having  this  in  mind,  it  is 
pretty  clear  that  the  future  will  see  less  automatic  and  more 
non-automatic  starting  gears  for  two-cylinder  receiver  com- 
pounds. 

136.  Automatic  Starting  Gears  Without  Intercept- 
ing Valves. — These  gears,  of  which  the  Lindner  is  the  best 
known  example,  give  practically  the  same  maximum  power 
at  starting   as  the   automatic  intercepting   valve   type,   but 
have  the   advantage  of  being  very  much  simpler.      In  fact, 
they  are  the  simplest  of  all  types.     All  that  has  been  said 
in  135  about  automatic   gears   applies   with  equal    force  to 
this  type.     They  work  well  under  average  conditions,  but 
the  unusual  demands  for  hauling  power  are  not  adequately 
provided  for. 

137.  Non-Automatic      Gears      With      Intercepting 
Valves    and  With    Separate    Exhausts   for  the   High- 
Pressure  Cylinders. — This  type  of  starting   gear    is    not 
adapted  to  permit  a  separate  exhaust  for  the  h.  p.  cylinder 


252  COMPOUND    LOCOMOTIVES. 

for  any  considerable  speed,  but  is  intended  solely  to  pro- 
vide starting  power  for  unusually  heavy  demands.  If  used 
continuously,  there  is  a  decided  loss  of  efficiency  of  the 
engine,  and,  in  some  designs,  the  fire  is  badly  torn  up  by 
the  force  of  the  blast.  It  is  intended  to  be  used  with 
discretion,  and  will  give  greater  hauling  power  to  the  com- 
pound at  slow  speed  than  is  possessed  by  a  single  expansion 
engine  of  equal  rating.  This  greater  power  is  given  by  the 
larger  dimensions  generally  used  for  compounds  for  both 
h.  p.  and  1.  p.  cylinders. 

138.  Starting  Gears  for  Four-Cylinder  Compounds. 
—When  four  cylinders  are  used,  whether  the  engine  be  a 
four  or  a  two-crank  locomotive,  or  with  or  without  receiver, 
there  is  practically  a  duplication  of  the  cylinder  power  on 
each  side,  and  if  steam  be  admitted  from  the  boiler  to  the 
1.  p.  cylinder  and  receiver  and  at  the  same  time  to  the  h.  p. 
steam  chest,  the  locomotive  will  have  greater  starting  power 
than  a  single  expansion  engine  of  equal  rating.  One  1.  p. 
cylinder  will  be  always  ready  to  act  with  great  power  and 
generally  one  h.  p.  cylinder  will  be  in  such  a  position  as  to 
assist.  Starting  gears  for  this  class  of  engine  need  no  espe- 
cial attention,  and  intercepting  valves  are  unnecessary. 
Generally  a  small  valve  is  provided  for  admitting  steam  into 
the  receiver  from  the  steam  pipe  whenever  there  is  steam 
therein  after  the  throttle  has  been  opened,  but  only  when 
the  reverse  lever  is  in  full  gear.  When  the  reverse  lever  is 
hooked  back  one  notch,  the  valve  is  closed  automatically. 
In  this  way  the  engine  can  be  run  with  increased  power  by 
admitting  steam  directly  into  the  1.  p.  cylinder  as  long  as 
the  reverse  lever  is  allowed  to  remain  in  full  gear.  The 
steam  supply  at  this  time  to  the  1.  p.  cylinder  direct  from  the 
steam  pipes  is  but  through  a  small  pipe,  and  as  the  speed 
increases  the  wire-drawing  through  this  pipe  increases  and  a 
much  smaller  amount  of  steam  is  used  in  this  way  per  stroke 
after  the  train  is  moving.  But  it  is  necessary  to  close  the 


SUMMARY    ABOUT    STARTING    GEARS.  253 

direct  supply  valve  and  not  permit  it  to  be  used  at  all  times, 
otherwise  the  economy  will  be  seriously  affected.  This 
has  led  to  a  demand  for  automatic  closure  when  the  reverse 
lever  is  hooked  up  one  notch. 


CHAPTER  XXII. 

REASONS  FOR  ECONOMY  IN  COMPOUND  LOCOMOTIVES. 

139.  Possibilities  of  Savings. — Compound  locomotives 
are  considered  to  be  more  economical  than  single  expan- 
sion locomotives  for  all  of  the  common  reasons  why  com- 
pound engines  generally  are  more  economical  than  single 
expansion  engines,  and  for  some  additional  reasons. 

The  principal  claims  for  better  efficiency  are  based 
upon  : 

(a)  Greater  expansion  of  steam,  45-52. 

(b)  Less  condensation  of  steam  due  to  lower  range  of 
temperature  in  cylinders,  69—72. 

(c)  Incidental  saving  due  to  better  action  of  the  blast 
on  the  fire,  and  the  somewhat  decreased  rate  of  combustion 
in  the  firebox,  83,  142-145. 

Other  reasons  than  these  are  frequently  given ;  but  the 
possible  saving  outside  these  features  is  too  small  to  be  con- 
sidered at  this  time  when  locomotives  are  designed  with  so 
little  attention  to  loss  of  heat  and  are  operated  with  such 
reckless  disregard  of  efficiency,  70,  145,  147. 

The  possibilities  of  saving  by  compounding  are  pretty 
clearlv  shown  by  indicator  cards.  It  can  be  determined 
within  5  per  cent.,  from  an  examination  of  indicator  cards 
taken  from  a  single  expansion  locomotive,  what  would  prob- 
ably be  the  saving  from  compounding,  provided  the  design 
of  compound  is  assumed  to  be  the  best  that  can  be  devised 
with  the  present  knowledge.  Many  of  the  reported  savings 
from  compounding  have  resulted  from  unfair  comparisons  in 
which  no  allowance  was  made  for  the  advantages  given  to 
the  compound,  such  as  higher  steam  pressure,  larger  grate 

254 


REASONS    FOR    ECONOMY.  255 

area,  and  increased  heating  surface.  As  this  is  now  well 
understood  by  railroad  men,  reported  savings  at  the  present 
time  are  looked  upon  with  suspicion,  and  this  it  is,  perhaps, 
as  much  as  anything  else,  which  recently  led  the  American 
Railway  Master  Mechanics  Association  to  appropriate  a  con- 
siderable sum  of  money  to  carry  on  a  laboratory  investiga- 
tion of  the  relative  merits  of  compound  and  single  expansion 
locomotives  at  the  Purdue  University,  on  the  plan  already 
commenced  by  Professor  Goss  of  that  university.  The 
theories  of  economy  due  to  compounding  are  so  complex 
and  involved  in  their  nature  that  mathematical  investigation 
is  practically  valueless  until  certain  factors  are  definitely 
determined,  and  it  is  useless  to  theorize  much  in  detail 
about  the  value  of  compounding  locomotives  until  more 
accurate  data  is  at  hand. 

140.  Saving  by  Greater  Expansion. — In  order  to  gain 
greater  expansion,  the  wire-drawing  common  in  locomotives 
must  be  greatly  reduced.  This  demands  better  valve 
motions  and  larger  ports  and  passages,  and  if  the  possibili- 
ties of  gain  in  expansion  are  to  be  fully  utilized,  the  steam 
pressure  must  be  considerably  increased.  With  our  present 
knowledge,  and  our  method  of  oiling  cylinders,  200  pounds 
per  square  inch  above  the  atmosphere  is  almost  the  limit  of 
boiler  pressure  for  good  practical  service,  7—19. 

The  saving  due  to  compounding  must  very  largely  result 
from  a  gain  in  expansion,  and  the  more  perfect  use  of  the 
higher  potential  of  increased  steam  pressures.  When  com- 
pared with  a  single  expansion  locomotive,  the  saving  of  the 
compound  will  vary  almost  directly  with  the  gain  in  the 
useful  work  from  a  given  weight  of  steam  by  greater  expan- 
sion, This  especially  applies  to  the  substitution  of  com- 
pounds for  single  expansion  locomotives  for  use  in  slow 
freight  service  on  heavy  grades  and  for  suburban  passenger 
work.  For  high  speed  passenger  work,  the  greater  loss, 
almost  universal  so  far,  in  compounds,  from  wire-drawing 


256  COMPOUND    LOCOMOTIVES. 

and  compression,  greatly  reduces  the  saving  otherwise  pos- 
'sible. 

It  may  not  be  clear  at  first  why  the  same  expansion 
cannot  be  obtained  in  single  expansion  locomotives  as 
in  compounds,  but  on  reflection  it  will  be  seen  that ;  the 
mechanical  difficulties  with  the  valve  motion  at  short  cut- 
offs ;  the  very  uneven  turning  power  applied  to  the  drivers, 
when  large  cylinders  are  used,  and  the  enormous  cylinder 
condensation  at  short  cut-offs,  compel  the  use  of  compounds 
for  high  grades  of  expansion.  With  cylinders  large  enough 
to  furnish  the  needed  expansion,  all  in  one  cylinder,  the 
tendency  to  slipping  drivers  is  so  great  as  to  prohibit  the 
-use  of  much  expansion  in  a  single  expansion  locomotive. 

141.  Saving  by  Reduction  of  Condensation. — To  gain 
the  saving  resulting  from  less  condensation  due  to  lower 
range  of  temperature  in  the  cylinders,  better  insulation  of 
the  steam  passages,  steam  chests  and  cylinders  must  be  had, 
and    no    great    gain    by   saving    in    condensation    may    be 
expected  unless  good  heat   insulation  is  provided,  69-72, 
151-152. 

142.  Saving  by  more  Complete  Combustion. — To  gain 
the  incidental  saving  due  to  a  better  action  of  blast,  there 
must  be  a  proper  arrangement  of  smoke  box  apparatus.     At 
the  present  time  no  one  seems  to  know,  because  of   lack  of 
accurate  data,  just  how  to  arrange  the  smoke  box  mechan- 
ism to  get  the  best  results.    The  practice  on  different  roads 
varies  altogether  too  much  to  indicate  any  uniformity  in 
opinion.     All  know  how  to  get  a  fairly  good  draft  with  a 
given   exhaust,  and  this   can  be  done  in  several  ways.     At 
the  present  time  each  new  lot  of  locomotives  is  experimented 
with  until  a  sufficient  blast  is  obtained,  and  there  the  matter 
is  dropped.      Hence,  at  the  present  time  no  safe  directions 
can  be  given  for  the  location  of  smoke  box  apparatus,  and 
the  designer  will  have  to  be  guided  by  the  prevailing  practice 
on  the  road  for  which  the  designs  are  made  and  make  such 


REASONS    FOR    ECONOMY.  257 

changes  after  the  engine  is  completed  as  will  give  satisfac- 
tory results.  This  much  neglected  matter  is  now  being 
investigated  by  the  American  Railway  Master  Mechanics 
Association,  145-147.  See  Fig.  147. 

143.  Saving  in  Fast  Express  and  Passenger  Service. 
— It  is  only  under  the  best  conditions  that  much  saving  can 
be  expected  from  compounds  in  fast  passenger  work.     That 
a  practical  saving  is  possible  in  this  service  must  be  admitted 
by  all  who  have  studied  closely  the  large  theoretical  saving 
possible  with  compounds.     Without  doubt  a  decided  saving 
will  be  found  in  fast  service  when  the  valve  motion  receives 
more  attention  and  the  steam  pressure  is  raised  to  about  200 
pounds  above  the  atmosphere.      In  some  instances  a  saving 
in  fast  service  has  already  been  reported,  and  it  is  undoubt- 
edly true  that  the  reported  savings  were  found,  but  whether 
the  economy  resulted   from  the  inferior  action  of  the  single 
expansion  engine  with  which  the  compound  was  compared, 
or  from  the  fact  that  the  passenger  service  was  so  slow  and 
heavy  as  to  give  the  compound  somewhat  the  same  advan- 
tage that  it  has  in   freight   service,   is  not  known.      Really 
accurate    tests   of   compounds    in    passenger    service    have 
never  been   made,  and  ordinarily  accurate  tests  have  ojily 
been   made  in  one  or  two  instances.     See  Appendixes  M 
and  N.     An  average  of  the  more  reliable  results  obtained 
shows   no    decided    advantage    for  •  the    compound    in   fast 
service,  but  this  may  result  from  the  inferior  action  of  the 
steam   regulating  apparatus,    12-19.       There   is  no    proof, 
however,  that  would  lead  to  a  safe  conclusion  that  compound 
locomotives  of  the  best  design  now  built,  or  when  built  with 
the  best  obtainable  knowledge,  are  not  more  economical  than 
single  expansion  locomotives  in  passenger  service. 

144.  Saving  in  Slow  Grade  Work  and  in  Freight 
and   Suburban    Service. — The    possible    saving    in    slow, 
heavy  freight  service  with   equally  good  designs  and  equal 
advantages  in  all  other  respects  for  compound  and  single 


258  COMPOUND    LOCOMOTIVES. 

expansion  locomotives,  varies  from  1 5  to  50  per  cent,  accord- 
ing to  the  conditions  of  operation.  In  general,  the  harder 
the  engiries  are  worked,  the  greater  will  be  the  saving  from 
compounding,  as  by  it  a  more  complete  utilization  of  the 
power  of  the  steam  will  be  obtained  by  greater  expansion, 
5,  1-2-19,  145. 

There  are  special  cases  where  incidental  economies  that 
have  not  been  mentioned  here  may  be  expected  ;  one  of 
these  is  in  elevated  and  suburban  service  where  it  is  neces- 
sary to  use  mufflers  on  the  exhaust  of  single  expansion 
engines.  These  mufflers  produce  a  back  pressure  varying 
from  i  o  to  20  pounds  per  square  inch  on  the  pistons  depend- 
ing upon  the  condition  of  the  mufflers.  They  quickly  become 
clogged  with  carbonized  cylinder  oil  and  cinder  from  the 
smoke  box  and  the  perforations  are  reduced  in  size  so  much 
as  to  require  boring  out  frequently.  With  the  compound  a 
wide  open  exhaust  nozzle  is  used,  as  the  final  pressure  of  the 
exhaust  is  reduced,  and  there  is  less  noise  than  with  a  single 
expansion  engine  equipped  with  mufflers.  The  saving  in 
fuel  by  reduction  in  back  pressure  probably  amounts  to  as 
much  as  the  saving  from  compounding  itself.  Such  inci- 
dental savings  as  this  and  also  some  incidental  losses,  depend 
upon  the  conditions,  and  an  estimate  of  a  probable  saving 
by  the  use  of  compounds  can  be  made  only  when  all  of  the 
conditions  are  known,  and  therefore  each  case  should  be 
studied  by  itself,  139-147. 

145.  How  Saving  is  Affected  by  the  Price  of  Fuel 
and  Rate  of  Combustion. — The  percentage  of  total  train 
expenses  that  will  be  saved  by  compounding  depends 
largely  upon  the  cost  of  fuel.  If  the  compound  is  well 
adapted  for  the  work  it  has  to  do  there  will  be  some 
advantages  incidental  to  the  less  amount  of  fuel  burned  in 
a  given  time  ;  it  will  be  easier  for  the  firemen,  and  there 
will  be  some  reduction  of  repairs  to  the  engine,  but 
the  main  portion  of  any  money  saving  must  be  expected 


REASONS  FOR  ECONOMY. 


259 


from  the  actual  saving  in  the  fuel  account.     Where  coal  is 
cheap,  say   from  90  cents  to   $1.50  per  ton,  the   saving  per 
year  in  dollars  and  cents  due  to  compounding  will  not  be, 
very  great,  but  where  coal  costs  from  7  to  10  dollars  per  ton,, 


O  5O  1OO  IbO  2OO 

COAL  USED  PER  SQ.  FT.  OF  GRATE  PER  HOUR-LBS. 

FIG.    147. 

Diagram  Showing  the   Relative  Values  of  Different  Fuels   and  the  Increased 
Boiler  Efficiency  with  Low  Rates  of  Combustion. 

as  in  some  of  the  Western  States,  or  from  12  to  22  dollars 
per  ton  as  in  Mexico  and  the  southwestern  United  States,, 
the  money  saving  due  to  compounding  is  very  great,  and 
amounts  to  more  than  the  maintenance,  deterioration  and 
interest  cost  for  the  entire  locomotive  equipment.  This 


260  COMPOUND    LOCOMOTIVES. 

has  been  the  experience  on  the  Mexican  Central  Railroad, 
where  the  price  of  coal  varies  from  18  to  23  dollars  per 
ton.  This  has  also  been  found  to  be  true  in  Austria, 
where  coal  is  expensive  and  of  inferior  quality,  that  will 
;give  an  evaporation  of  only  3^  pounds  of  water  per  pound 
of  coal. 

Fig.  147  shows  the  relative  value  of  different  kinds  of 
coals  when  burned  with  different  degrees  of  draft.  That 
is,  it  shows  how  the  efficiency  in  water  evaporation  in  a 
locomotive  boiler  decreases  as  the  coal  used  per  square  foot 
of  grate  per  hour  increases.  Incidentally  it  also  shows  the 
difference  between  English  and  American  coals  and  the 
greater  value  of  good  fuels. 

Fig.  148  shows  the  decrease  in  relative  cost  of  fuel  and 
other  train  expenses  per  ton  mile  of  cars  and  lading  with 
different  prices  for  fuel,  as  the  trains  are  increased,  and  will 
be  found  useful  in  reaching  a  conclusion  about  the  value  of 
a  compound  locomotive  on  any  given  road.  A  railroad 
manager  knows  that  where  fuel  is  cheap  even  a  large  saving 
in  weight  of  fuel  will  but  little  effect  the  total  cost  of  train 
expenses.  The  ratio  of  the  fuel  expenses  to  total  train 
expenses  is  given  by  Fig.  148.  It  is  evident  from  this 
diagram  that  outside  of  any  advantages  that  may  accom- 
pany the  use  of  compounds,  in  the  way  of  reducing  repairs 
and  decreasing  the  labor  of  the  firemen,  there  is  but  a  small 
percentage  of  total  train  expenses  to  be  saved  by  compound- 
ing when  coal  is  about  one  dollar  per  ton ;  but,  on  the 
other  hand,  it  is  also  clear  that  where  coal  costs  from  15  to 
20  dollars  per  ton,  a  20  per  cent,  saving  by  compounding 
very  materially  reduces  the  total  train  expenses. 

The  need  of  compounding  is  greater  on  some  roads 
than  on  others.  Where  the  locomotive  equipment  is  old- 
fashioned,  small  and  overworked,  and  where  the  boilers 
have  small  grates,  the  introduction  of  modern  heavy  com- 
pound locomotives  with  large  grates  frequently  brings  a 


REASONS    FOR    ECONOMY. 


26l 


saving  in  total  train  expenses  amounting  to  40  per  cent. 
This  arises  from  the  fact  that  heavier  trains  are  hauled  with 
the  same  train  crew  and  much  less  fuel  per  ton  mile  is  used  ; 
but  such  savings  are  not  due  to  compounding  alone  but  to 


COST  OF  COAL     PER    TON-DOLLARS. 

FIG.   148. 

Diagram  Showing  the   Comparative  Cost  of  Fuel  and  Other  Train  Expenses 
for  Varying  Prices  of  Fuel. 

the  combined  effects  of  heavier  engines,  larger  grates  and 
heating  surfaces,  and  the  saving  due  to  compounding.  Com- 
pounding generally  gives  also  some  indirect  advantages 
which  should  not  be  overlooked,  for  instance  it  is-  not  pos- 
sible to  give  to  large  locomotives  the  same  relative  boiler 
capacity  that  is  given  to  small  locomotives,  and  the  larger 
and  heavier  the  locomotive  the  smaller  is  the  relative  boiler 


262  COMPOUND    LOCOMOTIVES. 

capacity  that  can  be  provided.  There  is  a  limit  in  the 
increase  of  grate  area  at  which  a  fireman  cannot  fire  prop- 
erly, and  beyond  that  a  further  increase  gives  no  advantage. 
It  is  at  these  limits  of  increase  of  grate  area  and  steam- 
making  capacity  that  the  advantage  of  compounding  by 
reduction  of  total  amount  of  fuel  used  in  a  given  time  is  of 
great  benefit.  At  the  present  rate  of  increase  of  total  train 
loads  it  is  quite  clear  that  the  time  will  soon  be  at  hand 
when  compounding  of  locomotives  will  have  to  be  resorted 
to  in  order  to  reduce  the  demand  on  the  boilers.  See 
Fig.  147. 

Mr.  Axel  S.  Vogt,  Mechanical  Engineer  of  the  Pennsyl- 
vania Railroad,  in  summing  up,  recently,  the  probable 
advantages  of  compound  locomotives  for  future  work,  has 
said  in  effect  that  if  the  weight  and  speed  of  trains  con- 
tinues to  increase,  a  limit  of  grate  area  will  soon  be  reached, 
beyond  which  the  fire  cannot  be  properly  managed,  and  one 
possible  result  of  this  will  be  to  require  better  use  of  the 
steam  which  is  made.  And  any  further  increase  of  weight 
and  speed  of  trains  will  necessitate  the  introduction  of  more 
improved  methods  of  utilizing  the  steam,  so  that  it  appears 
that  the  compound  system  will  eventually  be  used  to  reduce 
the  demand  on  the  boilers. 

146.  Cost  of  Repairs. — To  offset  the  saving  by  the  use 
of  compound  locomotives,  there  is  some  extra  cost  of  main- 
tenance. The  additional  first  cost  will  range  from  100  to 
500  dollars  per  engine,  depending  somewhat  upon  the  size, 
but  mostly  upon  the  design.  The  actual  cost  of  the 
additional  parts  for  compounding  will  probably  not  be  over 
200  dollars  per  engine,  for  either  the  two-cylinder  receiver 
type  or  the  four-cylinder  non-receiver  type  ;  when  but  two 
cranks  are  used.  The  additional  cost  of  three  and  four- 
cylinder  types  with  receivers  and  with  three  or  four  cranks 
will  be  considerably  greater.  If  the  steam  pressure  on  the 
compound  is  higher  than  the  single  expansion  engine  with 


REASONS    FOR    ECONOMY.  263 

which  it  is  compared  in  cost,  the  compound  will  cost  some- 
thing more  for  the  stronger  boiler  that  will  be  necessary, 
but  this  addition  is  not  large,  and  the  total  cost  for  com- 
pounding a  locomotive  may,  for  the  purpose  of  compari- 
son, be  taken  at  250  dollars  for  the  complete  change. 

The  cost  of  maintenance  of  a  compound  will  be  greater 
in  the  cylinders  and  less  in  the  boiler.  The  somewhat 
better  and  more  uniform  draft  on  the  fire  and  the  lower 
rate  of  combustion  in  the  firebox  decreases  the  wear  and 
tear  on  the  furnace  plates  and  tubes.  Particularly  is  this 
true  for  such  locomotives  as  have  small  boilers,  and  which 
work  on  heavy  grades,  especially  in  those  sections  of  the 
country  where  fuel  is  cheap,  for  it  is  there  that  the  fires  are 
more  recklessly  handled,  less  attention  is  paid  to  fuel  econ- 
omy, more  fuel  is  burned  on  the  grate  in  a  given  time,  and 
firebox  failures  are  most  frequent,  particularly  if  the  water 
is  bad. 

In  this  country  locomotive  boiler  fires  are  forced  more 
than  the  fires  in  any  other  type,  except  steam  fire  engine  and 
torpedo  boat  boilers,  and  therefore  the  saving  of  coal  due 
to  compounding  under  average  conditions,  say  15  per  cent., 
reduces  the  forcing  of  the  fires  so  considerably  that  the 
effect  is  felt  at  once  by  the  fireman.  A  boiler  that  may 
be  difficult  to  fire  for  a  single  expansion  locomotive  may 
be  easily  handled  for  a  compound  doing  an  equal  amount 
of  work  in  the  same  time.  Where  the  feed  water  contains 
much  sediment  or  scale-producing  salts,  the  reduction  in 
the  forcing  of  the  boiler  accompanying  the  use  of  compound 
cylinders  is  a  decided  advantage,  and  one  that  makes  com- 
pounding worthy  of  consideration  even  where  the  fuel  cost 
is  a  small  part  of  the  total  cost  of  train  expenses. 

The  maintenance  of  the  cylinders,  pistons,  crossheads, 
guides,  steam  valves,  steam  chests,  steam  pipes  and  such 
other  parts  as  are  connected  to  the  cylinders,  and  which 
are  generally  affected  by  compounding,  amounts  to  about 


264  COMPOUND    LOCOMOTIVES. 

3  per  cent,  of  the  total  cost  of  locomotive  repairs.  The 
majority  of  all  locomotive  repairs  are  generally  those  which 
arise  from  the  boiler,  and  a  small  saving  in  boiler  repairs 
will  more  than  offset  the  total  cylinder  repairs.  If  the 
compound  system  increases  the  cylinder  repairs  100  per 
cent  ,  the  total  cost  is  small,  and  will  be  offset  fully  in  some 
cases  by  the  consequent  saving  in  boiler  repairs.  The  total 
cost  of  repairs  to  a  locomotive  is  not  far  from  1,200  dollars 
per  year  for  large  sizes.  If  the  additional  repairs  to  cylin- 
ders, etc.,  due  to  compounding,  is  as  much  as  100  per  cent, 
for  the  parts  affected,  the  additional  cost,  no  allowance 
being  made  for  the  saving  in  boiler  repairs,  is  but  36  dollars 
per  year,  and  if  there  is  any  saving  due  to  compounding 
that  is  worthy  of  the  name,  it  would  amount  in  money  to 
more  than  36  dollars  in  a  single  month,  even  with  coal  at 
$1.50  per  ton.  See  Fig.  148. 

147.  Methods  of  Operating  to  Gain  Economy. — It 
has  been  claimed  that  it  is  as  economical  to  work  a  com- 
pound engine  at  T6^  cut-off  in  the  h.  p.  cylinder,  and  wire- 
draw the  steam  through  the  throttle,  for  all  grades  of  work 
requiring  less  power  than  -f^  cut-off,  as  it  is  to  cut-off 
earlier  in  the  h.  p.  cylinder.  The  fallacy  of  this  for  slow 
speed  compound  engines  with  good  valve  gears,  or  for  high 
speed  engines  with  adequate  port  and  steam  passages,  and 
a  suitable  valve  motion,  is  perhaps  indicated  by  Fig.  45, 
which  shows  the  losses  due  to  wire-drawing  in  any  engine, 
compound  or  single  expansion,  resulting  from  the  loss  in 
potential  of  steam  pressure.  It  may  be  that  in  an  inferior 
compound,  where  the  steam  passages  and  valve  motion  and 
ports  are  such  as  to  give  a  very  bad  steam  distribution  at 
high  speeds  and  short  cut-offs,  it  would  be  more  eco- 
nomical to  use  a  longer  cut-off  and  wire-draw  the  steam 
through  the  throttle,  certainly  it  has  been  shown  that  the 
use  of  a  long  cut-off  and  a  partially  closed  throttle  gives 
more  power  at  high  speed,  and  the  highest  speeds  so  far 


REASONS    FOR    ECONOMY. 


265 


attained  by  compounds  have  only  been  accomplished  by 
this  plan.  But  this  is  quite  another  matter,  and  has  to  do 
only  with  power,  not  with  economy.  An  engine  may  not  be 
running  most  economically  at  high  speeds  when  it  is  gene- 
rating the  most  cylinder  power.  So  far  as  there  is  any 
evidence  at  all  in  the  matter,  everything  goes  to  show  that 
it  is  more  economical  to  run  with  an  open  throttle  at  all 
times,  when  the  boiler  is  not  priming,  than  it  is  to  wire- 
draw through  the  throttle.  Probably  the  most  economical 
compound,  all  other  things  being  equal,  is  one  that  will 


BOILER  PRESSURE. 


FIG.  149. 

Indicator   Cards   Showing   Steam  Use  When  the  Power  is  Regulated  by  the 

Throttle  Lever. 

run  with  sufficient  power  with  a  wide  open  throttle  at  cut- 
offs as  early  as  -^  of  the  stroke  of  the  h.  p.  cylinder  when 
at  high  speed.  A  compound  locomotive  should  be  designed, 
if  possible,  so  that  the  power  at  all  times  can  be  regulated 
by  the  reverse  lever,  and  the  throttle  be  kept  wide  open. 

Figs.  II  and  12,  Indicator  Cards  Nos.  I  to  14,  show  one 
method  of  running  compound  locomotives  ;  namely,  by 
changing  the  point  of  cut-off  as  the  speed  increases.  The 
effect  of  this  in  the  matter  of  wire-drawing  and  compression 
at  short  cut-offs  is  clearly  shown.  Table  A  gives  the  data 
for  these  cards.  Another  method,  and  one  which  some 


266 


COMPOUND    LOCOMOTIVES. 


compound  locomotive  builders  have  advised,  is  that  shown 
by  Indicator  Cards  Nos.  I  to  4,  Fig.  149.  The  data  for 
these  cards  is  given  in  Table  F  F.  This  plan  is  one  where 
the  cut-off  is  not  made  less  than  about  -f^  of  the  stroke  but 
the  power  is  regulated  by  the  throttle. 

TABLE  F  F. 


Card 

Boiler 

Revolutions 

Reverse  Lever 

Throttle 

Number. 

Pressure. 

per  Minute. 

Notch. 

opening. 

I 

155 

144 

4 

H 

2 

1  60 

228 

4 

H 

3 

1  60 

246 

5 

X 

4 

150 

308 

5 

X 

When  a  compound  engine  is  well  proportioned  for  the 
work  it  is  doing,  the  indicator  cards  at  average  speed  com- 
pare favorably  with  those  from  a  high  speed  stationary 
compound  engine.  This  is  shown  by  Cards  Nos.  I  to  5, 
Fig.  150,  which  were  taken  from  a  Baldwin  ten-wheel  com- 
pound passenger  engine  on  the  Erie  Railroad.  The  data 
regarding  these  cards  is  given  in  Table  G  G. 

TABLE    G  G. 


Card 

Number. 

Boiler 
Pressure. 

Revolutions 
per  minute. 

Speed. 
Miles  an 
Hour. 

I 

1  80 

120 

25.71 

2 

1  80 

1  60 

34-28 

3 

180 

1  60 

34.20 

4 

163 

140 

29.80 

5 

179 

172 

36.85 

This  question  of  the  proper  method  of  operating  has  two 
sides  to  it,  the  economical,  taking  into  consideration  only 
tlie  fuel  used ;  from  this  standpoint  it  is  better  to  run  with  a 
full  throttle  and  vary  the  power  by  changing  the  point  of 
cut-off.  The  other  point  of  view  takes  into  consideration 
only  the  capacity  of  the  locomotive  to  haul  trains  at  high 
speeds.  Viewed  from  this  last  standpoint  it  is  better  with 


REASONS  FOR  ECONOMY. 


267 


compound  locomotives  at  high  speed  not  to  regulate  the 
power  entirely  by  the  reverse  lever,  but  to  use  a  rather  long 
cut-off  and  run  by  the  throttle.  A  long  cut-off  gives  larger 
port  openings  and  a  later  exhaust  closure.  This  reduces  the 
wire-drawing  through  the  valve  and  decreases  the  compres- 


FIG,  150. 

Indicator  Cards  From  Vauclain  Compound,  Showing  Steam  Distribution  at 

Low  Speed. 

sion.  Compound  locomotives  have  more  power  at  high 
speeds  when  run  in  this  way.  As  has  been  shown  before, 
the  loss  of  potential  of  pressure  by  closing  the  throttle  carries 
with  it  a  loss  of  efficiency  that  is  not  made  up  by  the  gain  in 
the  saving  of  cylinder  condensation  by  the  superheating  that 
comes  from  wire-drawing  through  the  throttle.  See  Fig.  45. 
If  a  compound  locomotive  can  be  run  entirely  by  the  reverse 


268  COMPOUND    LOCOMOTIVES. 

lever  it  is  better  to  do  so,  but  if  the  valve  motion  is  such  as 
to  cause  excessive  compression  at  high  speed  there  is  only 
one  way  to  get  a  substantial  cylinder  power,  and  that  is  by 
using  a  long  cut-off  and  wire-drawing  steam  through  the 
throttle  to  reduce  the  amount  used  per  stroke  to  a  point 
where  the  boiler  can  keep  up  the  supply.  If  both  a  full 
throttle  and  a  long  cut-off  are  used  at  high  speed,  the  vast 
amount  of  steam  used  would  quickly  drain  the  boiler  and 
without  a  really  useful  result  in  the  way  of  an  increase  of 
speed  ;  this  is  for  the  reason  that  under  such  conditions  the 
increase  of  back  pressure  in  the  cylinders,  owing  to  the 
resistance  of  the  exhaust  nozzles,  to  a  considerable  extent 
offsets  the  greater  forward  pressure  on  the  piston. 


CHAPTER  XXIII. 

SELECTION  OF  TYPE  AND  DETAILS  OF  DESIGN  BEST  ADAPTED 
FOR  A  GIVEN  SERVICE. 

148.  Four-Cylinder  Four-Crank  Types. — This  type 
has  been  proposed  for  locomotives  in  order  to  provide  a 
more  uniform  turning  power  on  the  axles,  the  counter- 
balancing is. more  perfect,  and  the  starting  power  quite  suf- 
ficient, but  such  designs  as  have  been  brought  out  are  too 
complicated  for  practical  use.  See  Appendix  K.  Crank 
axles  are  not  desirable  for  locomotives  in  this  country, 
although  they  can  be  made  quite  strong  enough  to  with- 
stand the  service  here.  Axles  should  always  be  as  simple 
and  plain  as  possible,  and  all  bearings  should  be  readily 
accessible  for  American  service.  With  crank  axles  the 
bearings  cannot  be  readily  examined.  It  is  of  some  advan- 
tage also  to  have  all  of  the  axles  of  a  locomotive  alike  so 
that  the  stock  of  duplicate  parts  may  be  reduced.  Crank 
axles  need  careful  watching  for  cracks  from  the  day  they 
are  forged  to  the  time  they  are  discarded  except  while  in 
the  store-house,  and  their  use  puts  an  additional  tax  on  the 
motive  power  department,  particularly  so  as  the  points 
where  cracks  most  frequently  occur  are  not  easily  reached 
for  examination.  If  there  was  anything  of  real  value  to  be 
gained,  either  in  operation  or  efficiency,  by  the  use  of  crank 
axles,  undoubtedly  they  would  be  looked  upon  with  more 
favor,  but  so  far  as  can  be  seen  from  actual  records  of  ser- 
vice, the  plain  two-crank  outside-  connected  locomotive, 
whether  single  expansion  or  compound,  has  all  of  the  func- 
tions necessary  for  the  most  unusual  and  most  severe  ser- 
vice. Hence,  as  there  are  no  theoretical  advantages  in 

269 


27O  COMPOUND    LOCOMOTIVES. 

steam  efficiency,  and  no  advantages  in  practical  operation 
for  these  types  that  are  not  possessed  by  simpler  types,  they 
may  be  dropped  from  further  consideration,  133-134. 

149.  Three-Cylinder  Three-Crank  Types. — This  type 
is  open  to  the  same  objections  as  the  four-crank  four-cyl- 
inder type,  and  has  the  same  disadvantages  and  is  not  supe- 
rior to  the  simpler  types  in  any  particular.     This  type  is, 
however,    simpler    in    construction    than   the    four-cylinder 
four-crank  type,  128-132.     All   that  has   been   said   in  the 
preceding  about  the  four-cylinder  four-crank  types  applies 
with  equal  force  to  the  three-cylinder  three-crank  types,  148. 

150.  Four-Cylinder   Tandem   Two-Crank  Types.— 
This  type  is  made  with  and  without  a  receiver,  and  can  be 
operated  by  one  valve  for  each  pair  of  cylinders,  like  the 
Du  Bousquet  (Woolf )  tandem  engines  on  the  Northern  Rail- 
ways of  France,  118,  or  with  two  valves,  as  with  the  Mallet, 
Hungarian  and  Brooks  Locomotive  Works  designs,  124—127. 
Only    two  sets  of   guides,  crossheads,  connecting  rods  and 
link  motion  are  necessary  for  this  type,  the  same  as  with 
the  ordinary  single  expansion  engine.     So  far  as  the  theo- 
retical economy  or  the  starting  power  is  concerned,  it  mat- 
ters not  with  this  type  whether  a  receiver  be  or  be  not  used, 
or  whether  the  steam  be  controlled  with  two  valves,  or  one 
for  each  pair  of  cylinders.     The  receiver  designs  give,  per- 
haps, the  best  steam  distribution,  and  the  use  of  two  steam 
valves  gives  better   steam   port   openings    and    larger   and 
straighter  steam  passages  than  can  be  obtained  with  one 
valve,  and  therefore  for  high  speeds  the  receiver  type  with 
two  steam  valves  is  better,  as  the  steam  distribution  is  more 
readily   controlled   and  variations    can   be   made  with   less 
changes  in  details,  73-76. 

The  theoretical  efficiency  of  this  type  is  practically 
identical  with  that  of  other  four-cylinder  compounds,  and 
is  nearly  the  same  as  that  of  the  Vauclain  and  Johnstone 
types,  which  are  four  cylinder  two-crank  non-tandem  com- 
pounds, 151. 


SELECTION  OF  TYPE  FOR  A  GIVEN  SERVICE.   271 

Those  who  have  selected  the  tandem  in  preference  to- 
the  non-tandem  four-cylinder  type,  have  done  so  with  the 
expectation  of  gaining  a  mechanical  construction  of  pistons 
and  crossheads  that  is  more  theoretically  perfect,  120,  123. 
With  the  tandem  type,  the  annular  piston  of  the  Johnstone 
type  and  the  uneven  pressure  ori  the  crosshead  of  the  Vau- 
clain  type  are  avoided  ;  but,  on  the  other  hand,  more  parts 
are  added  and  the  front  cylinder  of  the  tandem  is  placed 
where  it  is  more  liable  to  damage  in  minor  wrecks  and  col- 
lisions. It  makes  the  front  truck  less  accessible  and  inter- 
feres with  some  kinds  of  snow-plow  and  flanger  attachments. 
The  same  number  of  piston  rod  stuffing-boxes  are  generally 
used  with  the  tandem  as  with  the  Johnstone ;  the  Vauclain 
has  one  less.  The  intermediate  stuffing-boxes  for  tandems 
are  generally  a  problem  difficult  to  solve,  127.  If  enough 
room  is  taken  to  make  them  readily  accessible,  the  over-all 
dimensions  of  the  cylinders,  lengthwise  of  the  engines  is 
greater  than  is  desirable,  124-125.  Hence,  designers  have 
been  led  to  attempt  to  combine  the  stuffing-boxes  between  the 
h.  p.  and  1.  p.  cylinders,  and  special  boxes  of  small  lengthwise 
dimensions  have  been  devised.  Such  combined  stuffing- 
boxes  as  have  been  put  in  actual  service  are  practically  inac-. 
cessible  without  great  labor  and  delay,  127,  so  they  may 
be  said  to  be  impracticable,  as  bad  leakages  cannot  be 
readily  discovered.  The  Mallet  design  of  cylinders  and 
stuffing-boxes  for  tandems,  125,  is  probably  the  best  that 
has  been  put  in  service,  but  perhaps  the  valve  rod  arrange- 
ment of  the  Hungarian  tandems  are  better,  124.  It  must 
be  said  that  the  tandem  type  has  greater  disadvantages  than 
the  two-cylinder  receiver  type  in  point  of  mechanical  con- 
struction, and  will  probably  be  more  inconvenient  in  a 
railroad  shop  and  cost  more  to  keep  in  repair  than  the 
Vauclain  or  Johnstone,  as  there  are  more  parts  to  care  for 
and  they  are  not  so  easy  of  access. 

Those  who  have  selected  the  tandem  types  have  done 


272  COMPOUND    LOCOMOTIVES. 

so  because  of  some  unusual  conditions  or  some  special 
service.  Two  at  least  of  the  tandems  that  have  been  built 
were  made  for  the  purpose  of  experiment. 

151.  Four-Cylinder  Non-Tandem  Two-Crank  Types, 
With  and  Without  Receivers. — None  of  this  type  with 
receivers  have  been  built.  Practically  this  class  is  repre- 
sented solely  by  the  Vauclain  and  Johnstone  types,  120, 
123.  Many  locomotives  of  the  Vauclain  type  have  been  in 
service,  and  the  results  of  practical  trials  are  numerous.  A 
number  of  the  Johnstone  type  have  been  put  into  service 
on  the  Mexican  Central  Railway,  and  so  far  as  can  be 
learned  no  practical  difficulties  have  been  encountered. 
The  theoretical  efficiencies  of  these  types  are  identical. 
The  Johnstone  has  been  used  under  exceptionally  favorable 
conditions  where  speeds  are  slow  and  fuel  is  high  in  price, 
and  a  very  great  money  saving  has  been  gained. 

The  Vauclain  has  been  used  under  all  common  con- 
ditions and  in  some  very  unusual  classes  of  services,  and 
the  results  have  been  correspondingly  varied.  In  cases 
where  the  conditions  have  been  the  same  as  those  under 
which  the  Johnstone  has  been  used,  the  savings  have  been 
equally  great,  and  in  other  cases  very  unfavorable  conditions 
have  led  to  little  or  no  saving.  With  these  compounds,  as 
with  all  others  the  conditions  control  the  saving  in  cost  of 
fuel. 

So  far  as  the  mechanical  construction  is  concerned,  the 
Vauclain  has  the  advantage  of  greater  simplicity  and  has 
parts  that  are  more  familiar  to  the  average  workman,  120- 
123.  The  uneven  pressure  on  the  crosshead  of  this  type, 
121,  led  many  at  first  to  expect  trouble  from  actual  service, 
but  it  has  been  pretty  clearly  demonstrated  that  so  far  as  the 
crosshead  and  piston  construction  is  concerned  this  type 
can  be  made  to  give  as  good  service  as  an  ordinary  single 
expansion  engine ;  but  more  care  is  required  in  design, 
better  selection  must  be  made  of  piston  rod  material,  and 


SELECTION    OF    TYPE    FOR    A    GIVEN    SERVICE.      273 

the  guides  must  be  kept  well  lined  up  to  prevent  as  much 
as  possible  the  rocking  motion  that  will  always  be  induced 
by  this  construction.  The  use  of  large  diameters  for  the 
h.  p.  piston  rod  has  led  to  much  criticism,  but  this  has  been 
the  result  of  a  too  rigid  piston  rod  connection  to  the  cross- 
head.  The  large  rods  were  used  to  remove  the  breakages 
of  piston  rods  at  the  crosshead  end  that  were  so  common  in 
early  designs.  It  is  not  believed  that  these  large  rods  are 
necessary  ;  in  fact  it  is  argued  with  some  reason  that  smaller 
and  more  flexible  (perhaps  longer)  piston  rods  would  be  less 
liable  to  break  than  the  larger  ones.  However,  the  piston 
rod  troubles  are  not  greater  with  the  Vauclain  type  than  with 
the  Laird  crosshead  type  of  single  expansion  engines  at  the 
present  time,  and  are  not  such  as  to  cause  apprehension. 

So  far,  the  Vauclain  type  has  been  used  with  a  single 
piston  valve  for  controlling  the  steam  in  both  cylinders, 
120,  and  the  results  have  been  very  satisfactory  in  slow 
service,  but  it  has  not  been  shown  yet  that  a  satisfactory 
steam  distribution  can  be  obtained  at  high  piston  speed  with 
a  short  cut-off  (^  of  the  stroke).  See  Figs,  n  and  12. 
The  builders  of  this  engine  have  advised  a  long  cut-off  (T6g- 
of  the  stroke)  and  a  regulation  of  the  power  by  the  throttle 
at  high  piston  speed,  147. 

Also  for  the  flat  slide  valve  arrangement  used  with  the 
.Johnstone  type  ;  it  has  not  been  shown  that  the  steam  dis- 
tribution is  good  at  high  speed  when  the  cut-off  in  the  h.  p. 
cylinder  is  less  than  half  stroke. 

It  is  not  as  economical  to  use  the  throttle  for  regulation 
at  any  speed  as  it  is  to  change  the  point  of  cut-off,  and  prob- 
ably some  change  in  the  valve  dimensions  ordinarily  used 
for  these  types  will  be  needed  to  gain  the  maximum  economy 
for  high  speeds. 

In  extreme  width  laterally  over  the  cylinders,  the  Vauc- 
lain has  the  advantage,  and  this  is  an  important  point  with 
some  conditions.  To  the  practical  mechanic,  the  Vauclain 


274  COMPOUND    LOCOMOTIVES. 

has  the  simpler  construction,  and  those  who  have  charge  of 
repairing  locomotives  will  be  of  the  opinion  that  the 
Vauclain  has  fewer  parts  to  watch,  and  it  is  probable  that 
with  it  the  piston  leakage  and  leakage  from  h.  p.  to  1.  p. 
cylinder  will  be  less  in  actual  service.  On  the  other  hand, 
the  valve  repairs  must  be  less  on  the  Johnstone,  as  the  parts 
are  simpler  and  are  of  ordinary  form.  The  Vauclain  valve 
bushing,  120,  is  not  a  simple  detail  and  cannot  be  renewed 
without  considerable  expense  ;  however,  it  wears  but  slowly 
when  the  valves  receive  proper  care  and  suitable  oiling. 

Of  all  the  four-cylinder  types  so  far  built,  the  Vauclain 
appears  to  be  the  most  practical  and  easiest  to  keep  in 
repair,  at  least  it  has  been*  shown  that  the  total  additional 
cost  of  cylinder  repairs  for  this  type  is  too  small  a  factor  to 
be  taken  into  account  in  a  consideration  of  the  value  of 
compounding  where  the  cost  of  fuel  is  of  any  considerable 
consequence. 

In  the  past,  those  who  have  chosen  the  Vauclain  type 
have  generally  done  so  because  of  its  greater  starting  power 
and  hauling  power  on  inclines  rather  than  from  any 
superiority  in  theoretical  efficiency.  The  Baldwin  Loco- 
motive Works  have  chosen  it  on  account  of  its  wide  appli- 
cation to  all  classes  of  service.  This  results  from  the  small 
over-all  dimensions  and  from  the  fact  that  it  is  a  type  of 
compound  that  will  do,  under  all  conditions,  all  that  a 
single  expansion  engine  will  do.  In  point  of  theoretical 
efficiency  it  is  not  equal  to  the  two-cylinder  type  with 
receiver,  as  it  has  more  cooling  surface  and  a  greater 
number  of  cylinders.  In  general,  where  other  conditions 
are  the  same,  and  there  is  the  same  degree  of  expansion  of 
steam,  engines  with  the  least  number  of  cylinders  will  be 
most  economical,  and  there  will  be  less  cylinder  condensation. 

The  two-cylinder  receiver  type,  with  an  independent 
exhaust  for  the  h.  p.  cylinder  at  starting,  is  the  strong  com- 
petitor of  the  Vauclain  type,  as  it  has  sufficient  starting 


SELECTION    OF    TYPE    FOR    A    GIVEN    SERVICE.       275 

power  and  somewhat  better  theoretical  economy,  and  has 
been  shown  to  give  better  steam  distribution  at  high  speeds 
with  short  cut-off.  See  Figs,  n  and  15.  No  tests  have 
been  made  that  conclusively  show  the  two -cylinder  type  to 
be  more  economical,  although  the  theory  of  steam  use 
would  point  that  way.  Yet  it  must  not  be  forgotten  that, 
taking  into  consideration  only  those  two-cylinder  and 
Vauclain  compounds  that  have  so  far  been  built  in  this 
country,  the  Vauclain  in  most*  cases  probably  has  the 
advantage  at  low  speeds  and  with  heavy  work,  as  the  1.  p. 
cylinder  capacity  has  been  made  much  larger  and  greater 
expansion  is  had  under  equal  conditions.  With  equal 
1.  p.  cylinder  capacity  the  two-cylinder  compound  will 
have  much  greater  over-all  dimensions,  and  for  large 
engines  this  is  a  point  of  weakness  in  the  design  that 
emphasizes  the  universal  adaptability  of  the  Vauclain  type.. 
With  a  double  1.  p.  cylinder,  as  has  been  proposed  by  Mallet 
(see  Fig.  100),  and  later  by  Lapage  (see  Fig.  28),  for  the 
nominally  two-cylinder  type,  the  needed  large  1.  p.  cylinder 
capacity  can<  be  obtained,  but  this  affects  the  theoretical! 
efficiency  somewhat  as  it  gives  larger  cooling  surfaces  and! 
one  more  cylinder.  All  this  goes  to  show  the  need  of  some 
accurate  experiment  at  this  time  to  determine  the  com- 
parative efficiency  of  compounds.  However,  it  is  quite 
certain  that  where  coal  is  expensive  or  the  conditions 
severe  a  considerable  saving  in  fuel  cost  will  result  from 
the  use  of  compounds  of  any  type,  providing  the  designs  of 
the  details  are  correct  and  the  proportions  properly  chosen* 
145. 

152.  Two-Cylinder  Two-Crank  Receiver  Types. — 
The  theoretical  efficiency  of  this  type  is  greater  than  any  of 
the  others  mentioned  here.  This  arises  from  the  less 
number  of  cylinders,  less  cooling  surface,  better  arrange- 
ment of  steam  passages  to  prevent  loss  by  radiation, 
possibility  of  reheating  in  the  receiver,  54,  and  the  more 


276  COMPOUND    LOCOMOTIVES. 

complete  control  of  cut-off  and  compression,  73-81.  In 
practical  service  no  superiority  has  been  shown  for  this  type 
in  this  country,  as  the  advantages  which  it  possesses  have 
/not  been  utilized.  To  get  the  necessary  1.  p.  cylinder  ca- 
pacity greater  over-all  width  has  been  thought  to  be  neces- 
sary, and  the  tendency  has  been  to  keep  the  cylinders,  both 
h.  p.  and  1.  p.,  smaller  than  they  should  be  This  appears 
from  Table  C  C,  Appendix  R. 

In  some  cases  it  has  already  been  found  necessary  to 
move  the  frames  inward  to  get  room  for  the  cylinders.  If 
the  double  1.  p.  cylinder  be  used,  see  Figs.  28  and  100,  the 
same  proportion  of  cylinder  capacity  to  the  work  to  be 
done  can  be  obtained  as  has  been  used  for  two-cylinder 
compounds  in  Europe,  and  for  four-cylinder  compounds  in 
this  country. 

In  this  type  there  is  every  chance  to  make  a  good 
insulation  for  all  of  the  steam  passages,  and  there  is  no  excuse 
for  placing  h.  p.  steam  on  one  side  of  a  yz  -inch  wall  and 
1.  p.  steam,  or  the  cooler  atmosphere,  on  the  other  side,  as  is 
generally  done.  This  possibility  of  better  heat  insulation 
has  not  been  utilized,  except  in  the  case  of  the  Old  Colony 
compound.  See  Figs.  72-75.  The  amount  of  re-heating  in 
the  receiver  will  vary  with  the  temperature  of  the  smoke 
box  and  the  speed  of  the  engine.  By  using  a  large  copper 
receiver  with  a  volume  not  less  than  three  times  that  of  the 
h.  p.  cylinder  such  re-heating  as  it  is  practicable  to  gain  may 
be  had.  As  the  re-heating  in  the  receiver  is  done  by  the 
waste  heat  in  the  furnace  gases,  all  the  re-heating  that 
takes  place  is  clear  gain,  and  in  this  way  it  differs  from 
re-heating  by  boiler*steam,  54. 

As  the  cut-off  in  the  cylinders  of  this  type  can  be 
readily  varied  there  is  a  better  chance  to  adjust  the  valves, 
73-81,  for  the  average  conditions  of  operation  than  is  the 
case  with  four-cylinder  engines,  with  one  valve  for  two 
cylinders  and  this  more  complete  control  of  the  distribution 


SELECTION  OF  TYPE  FOR  A  GIVEN  SERVICE.   277 

of  steam,  if  taken  advantage  of,  will  give  to  this  type 
greater  efficiency  at  high  speeds. 

153.  In  General  about  a  Selection  of  a  Suitable 
Design. — The  designer  is  confronted,  so  far  as  economy 
is  concerned,  with  but  practically  two  types,  viz.,  the  two- 
cylinder  two-crank  compounds  with  receiver,  and  the  four- 
cylinder  two-.crank  compounds  with  and  without  receiver. 
To  the  first  belong  the  compounds  of  Mallet,  von  Borries, 
Worsdell,  Lindner,  Golsdorf  (Austrian) ,  Schenectady,  Rhode 
Island,  Dean,  Brooks  two-cylinder,  Richmond,  Chicago, 
Burlington  &  Quincy  Railroad,  Pennsylvania  Railroad, 
Rogers,  Cooke  and  Pittsburgh  compounds.  To  the  second 
class  belong  the  Vauclain,  Johnstone,  Brooks  Tandem, 
Mallet  Tandem,  Hungarian  Tandem,  and  the  Du  Bousquet 
types.  So  far  as  practical  experience  with  compound  loco- 
motives goes,  there  is  no  evidence  to  show  that  any  one 
of  these  types  has  the  advantage  of  the  others  in  point  of 
economy,  but  there  are  many  points  of  claimed  advantage 
for  each.  All  that  is  certain  is,  that  the  four-cylinder 
type  is  better  in  starting  trains,  and  does  more  satisfactory 
work  on  grades  than  the  two-cylinder  type  with  automatic 
starting  gear,  but  is  not  superior  in  this  respect  to  the  two 
cylinder  type  with  a  separate  exhaust  for  the  h.  p.  cylin- 
der. 

The  four-cylinder  type  will  start  trains  satisfactorily, 
and  the  starting  gear  needs  but  little  consideration.  What 
needs  most  attention  is  the  mechanical  construction  of  the 
driving  mechanism  and  the  arrangement  of  the  valve  motion 
and  steam  distribution. 

With  the  two-cylinder  compound  the  starting  power 
needs  first  consideration.  The  mechanical  construction  is 
generally  good.  The  valve  motion  and  steam  distribution 
can  be  readily  made  satisfactory  by  attention  to  the  well- 
known  principles  of  designing  steam  ports  and  passages,  and 
the  selection  of  a  proper  valve  travel,  and  thereafter  adjust- 


278  COMPOUND    LOCOMOTIVES. 

ing  the  cut-offs  to  suit  the  average  working  of  the  engine. 
This  adjustment  may  be  made  in  several  ways,  73-81. 

At  the  present  time  only  two  types  of  compounds  have 
seen  sufficient  service  in  this  country  to  prove  their  practi- 
cability. These  are  the  two-cylinder  two-crank  receiver 
types,  and  the  four-cylinder  non-tandem  two-crank  receiver 
type,  or,  more  concisely,  the  two-cylinder  compound,  and 
the  Vauclain  and  Johnstone  compounds. 

It  has  been  shown  that  the  two  and  four-cylinder  two- 
crank  outside  connected  locomotives  are  perfectly  practical 
machines,  so  far  as  steam  use  and  hauling  of  trains  is 
concerned,  and  therefore  there  is  no  advantage  in  the  intro- 
duction of  a  third  or  fourth  crank,  with  the  consequent 
complication  of  parts. 

It  is  not  apparent  that  either  the  three  or  four-crank 
types  will  ever  come  into  general  use,  for  the  reason  that 
simplicity  of  design  is  of  first  importance  in  locomotive  con- 
struction, and  so  long  as  locomotives  with  two  cranks  can  be 
operated  practically  with  such  excellent  results  as  at  the 
present  time  (the  theoretical  saving  being  even  greater  with 
the  two-crank  than  with  the  three  or  four-crank  types)  there 
will  be  little  chance  for  a  general  introduction  of  compounds 
with  more  than  two  cranks.  The  single  exception  to  this 
statement  is  in  the  case  of  double-bogie  locomotives,  in 
which  there  are  necessarily  four  cranks  per  engine  ;  such 
engines  are  in  fact  but  two  engines  combined,  each  of  which 
is  a  two-crank  compound,  and  all  the  remarks  that  have 
been  made  here  regarding  the  two-crank  compounds  apply 
with  equal  force  to  the  double  bogie. 

It  is  a  pertinent  fact  that  while  the  three-cylinder  three- 
crank  compound  has  been  given  every  advantage  and  possi- 
bility of  success,  and  every  opportunity  to  show  its  practical 
value,  both  in  England  on  the  Northwestern  Railroad,  and 
in  France  on  the  Northern  Railways,  and  in  this  country  on 
the  Pennsylvania  Railroad,  yet  no  material  advance  has  been 


SELECTION  OF  TYPE  FOR  A  GIVEN  SERVICE.   279 

made  in  the  introduction  of  this  type  ;  while  during  the 
same  period  the  use  of  the  two-cylinder  compound  in 
England  has  been  largely  increased,  and  the  four-cylinder 
two-crank  non-receiver  type  has  been  given  preference  to 
all  other  types  on  the  Northern  Railways  of  France. 

All  further  consideration  of  locomotives  having  crank 
shafts  may  be  dropped,  for  the  reason  that  they  have  no 
real  nor  apparent  theoretical  or  practical  advantages. 

The  question  of  hauling  trains  in  case  of  accident  to 
machinery  is  an  important  one  from  an  operating  stand- 
point. Compounds  with  h.  p.  and  1.  p,  cylinders  on  the 
same  side  can  haul  trains  with  one  side  disconnected.  With 
a  separate  exhaust  for  the  h.  p.  cylinder  and  sufficient  steam 
supply  direct  to  the  1.  p.  cylinder,  the  two-cylinder  type 
can  always  haul  trains  when  only  one  side  is  disabled. 
Without  separate  exhaust  for  the  h.  p.  cylinder  this  type  is 
practically  helpless  in  case  of  a  broken  1.  p.  steam  chest,  or 
if  there  is  a  too  small  steam  supply  to  the  1.  p.  cylinder  and 
the  h.  p.  steam  chest  is  broken.  Where  the  cylinders  and 
steam  chest  remain  intact  on  both  sides,  this  type  can  haul 
a  train  at  considerable  speed  without  an  exhaust  from  h.  p. 
cylinder  when  either  side  is  disconnected. 

So  far  as  the  details  of  the  cylinders  of  compound  loco- 
motives are  concerned,  other  than  those  that  are  referred  to 
in  these  pages,  including  heat  insulation,  the  best  that  can 
be  done  is  to  follow  compound  stationary  engine  practice, 
making  due  allowance  for  the  wide  variation  of  power 
demanded  in  locomotive  operation,  more  particularly  in 
starting  trains  quickly  from  a  period  of  rest,  and  in  hauling 
up  short,  steep  inclines  on  otherwise  level  roads. 


APPENDIX. 


NOTE.— In  the  following, 
v  =  volume  of  h.  p.  cylinders  in  cubic  inches. 

y=    "    "  i-p.     

;  C=      "       "  receiver  " 

R=  ratio      "  volumes  of  h.  p.  and  1.  p.  cylinders. 

A.  Example  of  Calculation  for  Mean  Effective  Pressure  during  one  Stroke,  7. — 
Let  the  gauge  pressure  at  the  point  b,  Fig.  i,  be  145.3  pounds  per  square  inch,  so 
that  the  absolute  pressure  will  be  160  pounds.     As  cut-off  takes  place  at  one-half 
stroke  the  ratio  of  expansion  r  =  2,  and  therefore  the  final   pressure  in  the  h.  p. 
cylinder  will  be  one-half  of  160  =  80  pounds.     From  the  tables  previously  referred 
to  we   find  that  for  r  —  2,  p,n  -  .847  pi.  and    therefore   pm  =  .847  x  160  =  135.5 
pounds  absolute  pressure,  which  is  the  mean  pressure  between  aandc  measured  from 
the  zero  line  of  pressure.  

B.  Example  of  Calculation  for  Mean  Effective  Pressure  during  Expansion ,  7. — 
For  example,  the  pressure  at  b,  Fig.  3,  is  160  pounds  and  the  volume  at  c  is  twice 
that  at  b.     The  ratio  of  expansion  is  therefore  2,  and  t>y  reference  to  a  table  of 

hyperbolic  logarithms  we  find  pm  -  160  '—21  =  160  X   .693  =  110.9  pounds  between 

2—1 

b  and  c.     This  is  for  one-half  of  the  stroke,  and  for  the  first  half,  from  a  to  b,  the 
mean  pressure  is  160  pounds,  therefore  the  average  for  the  whole  stroke  would  be 

160  +  110.9  = 


C.  Example  of  Calculation  for  Pressure  in  the  Receiver*  21. — In  the  present  case. 
Fig.  i,  assume  the  capacity  of  the  receiver  to  be  equal  to  that  of  the  h.  -p.  cylinder, 
or  C  =  v,  and  let  the  pressure  at  e  be  taken  at  96  pounds.     At  d  the  steam  fills  the 
h.  p.  cylinder  +  receiver,  and  at  e  fills  one-half  the  h.  p.  cylinder  +  receiver;  there- 
fore the  compression  is  from  v  +  C  =  2  v  to  .5  v  +  C  =  1.5  v,  and  the  ratio  of  com- 
pression is  2  v  -+-   1.5  v  =  i.  33.     The  pressure  at  d  is  then  96  X  .75  =  72  pounds, 
and  the  mean  pressure  between  e  and  d  is  96  X  .86  =  82.6  pounds.     At/the  volume 
occupied  is  that  of  one-half  the  1.  p.  cylinder  +  receiver.     Assuming  for  the  present 
case  that  the  1.  p.  cylinder  is  2.5  times  the  h.  p.  cylinder,  or  R  =  2.5    the   expansion 

will  be  from  1.5  v  to  2'^  v    +  C  =  2.25  v,  or  the  ratio  of  expansion  is  2.25  v  -+-  1.5  = 

2 

1.5.      The   pressure   at  f  is  then  96  X  .67  =  64  pounds,  and  the   mean  pressure 
between  e  and /is  96  x  .81  =  77.8  pounds. 

D.  Final  Pressure ;  Total  Expansion ,  45-52. — In  an  elementary  compound  en- 
gine, a  certain  fraction  of  the  h.  p.  cylinder  is  filled  with  steam  from  the  boiler  at  each 
stroke,  and  after  expanding  in  both  cylinders  this  mass  of  steam  finally  fills  the  1.  p.  cyl- 
inder before  it  is  exhausted  into  the  atmosphere  or  condenser.     For  example,  if  the 
cylinder  ratio  is  2.5  and  the  h.  p.  cut-off  is  at  one-half  stroke,  .5  v  is  the  volume  admitted 
from  the  boiler  at  each  stroke,  and  this  finally  fills  the  volume  2.5  v  before  it  is  exhausted. 

281 


282  COMPOUND    LOCOMOTIVES. 

The  steam  is  therefore  expanded  to  5  times  its  initial  volume,  or  the  ratio  of  total 
expansion  is  5,  and  the  final  pressure  at  which  it  is  exhausted  will  be  -i-  of  the 
initial  pressure,  or  32  pounds  in  the  case  we  have  used  for  purposes  of  illustration. 
Similarly,  if  the  h.  p.  cut-off  was  at  %  stroke  the  ratio  of  total  expansion  would  be 
2.5  X  |  =  ZJL  -  6'i,  and  the  final  absolute  pressure  in  the  1.  p.  cylinder  would  be 
23Q  of  160  =  24  pounds.  It  will  be  noted  that  the  only  data  required  in  determining 
the  total  expansion  and  final  pressure  in  an  elementary  engine  are  the  ratio  of  the 
cylinders  and  the  h.  p.  cut-off,  or,  in  other  words,  these  results  are  independent  of 
the  capacity  of  the  receiver  and  of  the  1.  p.  cut-off.  The  effect  of  the  size  of  the 
receiver  is  seen  in  the  shape  of  the  indicator  cards  due  to  the  compressions  and  expan- 
sions ;  but  how  many  and  how  large  these  variations  are  does  not  affect  the  final 
pressure.  The  office  of  the  1.  p.  cut-off  is  to  control  the  division  of  the  work  between 
the  two  cylinders.  In  a  compound  engine,  which  exhausts  into  the  atmosphere,  the 
steam  can,  under  the  best  and  most  favorable  conditions,  be  expanded  economically 
until  the  boiler  pressure  is  reduced  to  the  atmospheric  pressure.  Steam  at  160 

160 
pounds  absolute  could,  therefore,  be  expanded  =  n  times,  nearly. 


E.  Drop  in   Pressure  in  Receiver,  26. — Taking  f?  =  2.5,  C=  v,  h.  p.  cut-off  at 
%  stroke,  and   1.  p.  cut-off  at  %  stroke,  we   have   the   final  pressure  at  the  end  of 
the  expansion   in   the   1.  p.  cylinder  equal  to  ^  of  160,  or  32  pounds.     The   ratio 
of    expansion   in  the  1.  p.  cylinder  is  2,  therefore   the    pressure  at  the   point  /  is 
32  X  2  =  64  pounds.     Then,  knowing  the  ratio  of  expansion  from  e  to  /,  as  already 
calculated  to  be  1.5,   we   have   the  pressure   at   e  =  64  x  1.5  =  96  pounds,  which 
was  assumed  for  the  time  in  calculating  the  variations  of  pressure  in  the  receiver. 
Working   back   from   this   still   further,    we   find    the   pressure   at   d  as   before,    72 
pounds,  and  as  the  pressure  at  c  is   80  pounds,    there  has  been   a  drop  in  pres- 
sure of  8  pounds   when  the   h.  p.  exhaust  opened      When   the   1.  p.   steam   valve 
closed  at  /,  the  pressure  of  the   steam   left   in   the  receiver  was  64  pounds.     Then 
when  the  h.  p.  exhaust  opened,  the  steam  which  filled  the  h.  p.  cylinder  at  a  pres- 
sure of  80  pounds  mixed  with   this,   and  gave   a  resulting  pressure  of  72  pounds. 
To  prevent  drop  in  an  elementary  engine,  it  is  only  necessary  to  adjust  the  cut-off 
of  the  1.  p.   cylinder  so  that  the  volume  of  steam    drawn  by  it  from   the   receiver 
equals  that  of  the  h.  p.  cylinder.     For  instance,  with  dimensions  already  given  in  this 

paragraph,  it  will  be  evident  that  when  the  1.  p.  cut-off  is  at  — -  or  |  of  the   stroke, 

here  will  be  no  drop,  because  |  of  the  1.  p.  cylinder  is  equal  to  the  whole  h.  p. 
cylinder  in  volume,  and  if  we  withdraw  from  the  receiver  at  each  stroke  a  volume 
which  is  equal  to  that  received  from  the  h.  p.  cylinder,  the  pressure  in  the  receiver 
will  not  be  reduced.  This  can  also  be  readily  shown  by  calculating  back  from  the 
final  pressure  in  the  1.  p.  cylinder  as  before.  Suppose  e  f  to  represent  -|  of  the 
1.  p.  stroke  instead  of  ^ ,  as  shown  in  the  figure,  then  the  pressure  at  /  would  be 
32  X  §  =  80  pounds,  which  would  be  the  pressure  in  the  receiver  when  the  h.  p. 
exhaust  opened;  and  as  this  is  also  the  final  pressure  in  the  h.  p.  cylinder,  there  would 
be  no  drop.  There  is,  of  course,  always  more  or  less  drop  due  to  wire-drawing  and 
friction  in  passages  which  cannot  be  prevented,  and  it  must  also  be  borne  in  mind 
that  all  of  these  calculations  are  based  on  the  assumption  that  pressures  vary  inversely 
as  the  volumes.  

F.  Mean  Effective  Pressure;  Equivalent  Pressure  in  One  Cylinder,  7. — With  the 
data  already  used  the  mean  forward  pressure  in  the  h.  p.  cylinder  was  found  to  be 


APPENDIX.  283 

135.5  pounds.  The  mean  receiver  pressure,  or  h.  p.  back  pressure,  is  80.2  pounds, 
and  thus  the  mean  effective  pressure  in  the  h.  p.  cylinder  is  135.5  —  8o-2  =  55-3 
pounds.  For  the  1.  p.  card,  the  mean  pressure  between  e  andyf  was  found  to  be  77.8 
and  the  pressure  at/was  64  pounds.  The  mean  presssure  between / and  g  is  64  X 

.693  =  44.4  pounds.     The  mean  forward  pressure  for  the  stroke  is  then  TLL — 

=  61.1  pounds,  and  assuming  a  back  pressure  of  18  pounds,  or  3.3  above  the  atmos- 
pheric pressure,  the  1.  p.  mean  effective  pressure  will  be  61.1  —  18  =  43.1  pounds. 

As  the  ratio  between  the  cylinder  areas  is  2.5,  assuming  the  stroke  to  be  the  same 
in  both  cylinders,  as  it  generally  would  be  in  practice,  one  pound  per  square  inch  on 
the  1.  p.  piston  is  equivalent  to  2.5  pounds  per  square  inch  on  the  h.  p.  piston.  We 
can  thus  readily  find  the  effective  pressure  in  a  single  cylinder,  which  is  equivalent  to 
the  effective  pressure  in  the  two  cylinders  of  the  compound  engine.  Ordinarily  the 
mean  pressure  is  thus  referred  to  the  1.  p.  piston,  although  a  reference  to  the  h.  p. 
piston  is  more  convenient  for  some  purposes.  In  the  present  case,  the  effective  h.  p. 

pressure  referred  to  the  1.  p.  piston  is  55'3  _  22il    -phe  total  effective  pressure  referred 

2-5 

to  the  1.  p.  piston  is  then  22.1  +  43.1  =65.2  pounds.  From  this  we  find  that  the  propor- 
tion of  the  total  work  which  is  done  by  each  cylinder  is,  in  h.  p.,  J—  =  .34,  and  in  1.  p. 

65.2 

43-1  scr.66.  If  the  pressures  are  referred  to  the  h.  p.  piston,  we  have  43.1  x  2.5  + 
65.2 

55.3  =  107.8  +  55.3  163.1  as  the  equivalent  pressure  in  one  cylinder  of  the  same 
size  as  the  h.  p.  cylinder.  Formerly  common  practice  was  to  make  the  h.  p.  cylinder 
of  a  compound  locomotive  of  the  same  size  as  one  cylinder  of  the  single  expansion 
engine  which  it  is  intended  to  replace.  On  this  basis  the  theoretical  compound 
engine  under  discussion  would  be  developing  the  same  work  as  the  single  expan- 
sion engine  when  the  latter  was  developing  a  mean  effective  pressure  of  %  of 
163.1  =  81.6  pounds  in  each  cylinder. 


G.  Example  of  Calculation  for  Mean  Effective  Pressure  when  Clearance  is  taken 
into  Account,  4. — As  an  example  of  the  application  of  the  formula,  let  the  appa- 
rent cut-off  be  at  %  stroke  with  8  per  cent,  clearance.  The  actual  ratio  of 

expansion  is  then    T   *  '°    =  2.63,  and  the  mean  pressure  between  b  and  c  will  be 

.33  +  .08 

/,  1?_Z  =  .594/i.     This    is   for  %  of    the  stroke,  and  for  the   first  third  the  mean 
1.63 

pressure  equals /a .     The  mean  for  the  stroke  is  therefore  2  x  -594 /*i  +  P\    _  .73  ^. 
The  mean  pressure  calculated  by  formula  without  correction  would  be 


H.  Derivation  of  Formula  for  Tractive  Force,  62. — The  work  done  in  the  cylin- 
ders in  inch-pounds  is  2  X  area  in  square  inches  X  mean  effective  pressure  X  twice 
the  stroke  in  inches  =  2X  ^  ^  d2  X  ^>  X  2  s. ;  that  at  the  rim  of  the  driving  wheels 
is  the  pull  in  pounds  X  the  circumference  of  the  wheel  in  inches  =  T  X  7r  D;  there- 
fore, 

2  X  &  if  d*  X  p  X   2  s  _  d?p  s. 


284  COMPOUND    LOCOMOTIVES. 

/.  Some  further  Discussion  of  Three-  Cylinder  Three  -Crank  Compounds,  129- 
134.  —  In  the  three-cylinder  receiver  type  the  ratio  of  the  volumes  of  the  cylinders  can 
be  made  greater  than  "is  practicable  with  two  cylinders,  and  by  a  proper  arrangement 
of  cranks  a  more  uniform  rotative  power  can  be  secured. 

The  two  arrangements  of  three-cylinder  compound  engines  that  have  been  applied 
to  locomotives  are  with  one  h.  p.  and  two  1.  p.  cylinders  by  the  Northern  Railway 
of  France,  with  two  h.  p.  cylinders  and  one  1.  p.,  the  arrangement  of  the  Webb  type, 


Steam  Distribution,  —  The  fundamental  theory  of  the  elementary  three-cylinder 
compound  engines  does  not  differ  from  that  of  two-cylinder  compound  engines.  The 
only  differences  which  exist  are  the  result  of  the  relative  angles  of  the  cranks,  and  are 
to  be  found  in  the  variations  in  the  turning  moments  and  in  the  variations  in  pressures 
in  the  receivers.  Each  case  must  be  individually  analyzed,  and  the  only  difference 
between  such  analyses  and  those  already  given  for  two-cylinder  engines  is  the  greater 
complication  which  arises  from  having  three  cranks  to  consider  instead  of  two.  As  an 
example  of  the  method  to  be  preferably  followed  in  attempting  such  an  investigation, 
an  arrangement  of  cranks  which  has  been  used  for  a  locomotive  is  selected.  In.  this 
form  the  low-pressure  cranks  are  at  right  angles  and  the  high-pressure  crank  makes 
angles  of  135  degrees  with  them.  In  the  first  place  we  assume  the  following  data  :  In 
the  high-pressure  cylinder,  cut-off,  .75;  release,  90;  compression,  .90;  in  the  low- 
pressure  cylinders  the  same  distribution. 

In  Fig.  151  are  shown  successive  positions  of  the  three  cranks,  h  representing  the 
high-pressure  crank,  L  one  low-pressure  crank,  and  /  the  other.  Assuming  the  direc- 
tion of  the  revolution  to  be  as  indicated  by  the  arrow,  an  exhaust  takes  place  from  the 
high-pressure  cylinder  when  its  crank  is  at  hl.  One  low-pressure  crank,  /j  ,  is  then  just 
commencing  a  stroke,  and  the  other  Llt  has  accomplished  about  .57  of  a  stroke,  the 
effect  of  the  angularity  of  the  connecting  rods  being  neglected.  From  these  positions 
there  is  free  communication  between  the  three  cylinders  and  the  receiver  until  L 
moves  to  L2,  where  the  cut-off  takes  place  in  that  cylinder,  the  other  1.  p.  crank  being 
then  at  /2  and  the  h.  p.  crank  at  hi.  From  these  positions  expansion  continues  in 
the  cylinder  L,  while  th.er.e  is  still  free  communication  between  the  other  1.  p.  cylinder, 
the  receiver  and  the  h.  p.  cylinder  until  the  1.  p.  crank  L  arrives  at  L3,  when  steam  is 
again  admitted  to  that  cylinder  for  the  return  stroke.  The  other  1.  p.  crank  is  then  at 
/3,  and  the  h.  p.  crank  is  at  /ts.  All  three  cylinders  are  now  again  in  communication, 
and  remain  so  until  the  cut-off  position  l\  is  reached,  the  other  cranks  then  being  at 
Z,4  and  /z4.  The  two  cylinders  which  are  represented  by  h  and  L  remain  in  communi- 
cation until  the  positions  numbered  5  are  reached,  when  steam  is  again  admitted  to 
the  cylinder  /.  Soon  after  this  the  h.  p.  exhaust  takes  place  at  h&,  and  a  fresh  supply 
of  steam  is  admitted  to  the  receiver,  from  which  it  enters  both  1.  p.  cylinders  whose 
cranks  are  at  L6  and  /6.  These  positions  correspond  to  those  numbered  i  ,  the  direc- 
tion of  the  piston  movement  only  being  changed.  It  is  clear  that,  when  the  exhaust 
takes  place  from  the  h.  p.  cylinder,  the  1.  p.  piston  corresponding  to  /  is  always  near 
the  beginning  of  a  stroke,  while  the  other  is  near  the  middle  of  its  stroke.  The  effects 
of  this  distribution  in  the  1.  p.  cylinders  are  shown  in  Fig.  152  by  indicator  cards, 
which  are  constructed  on  the  assumption  of  rapid  valve  movements  and  neglecting 
the  irregularities  which  are  caused  by  the  connecting  rods.  The  cards  are  not  drawn 
to  a  scale  and  the  variations  in  pressures  are  purposely  exaggerated.  With  a  relatively 
large  receiver  the  drop  in  pressure  at  /a  and  L5  will  be  very  small.  In  practice  the 
readmission  at  i  would  produce  a  hump  in  the  card  L,  while  the  card  /  would  have  a 
form  which  would  apparently  indicate  that  the  valve  was  late  in  opening. 


APPENDIX. 


At  earlier  points  of  cut-off  somewhat  different  results  will  be  found.  These  are 
illustrated  by  Figs.  153  and  154,  in  which  it  is  assumed  that  cut-off  takes  place  at  .4 
and  release  at  .75  of  the  stroke  in  all  three  cylinders.  Taking  the  direction  of  revolu- 
tion as  before,  when  release  occurs  in  the  h.  p.  cylinder  at  h\,  one  1.  p.  crank  is  at  L\ 
and  the  other  is  at  l\ .  A  very  slight  movement  brings  the  crank  L  to  its  cut-off  posi- 
tion L'i,  soon  after  which  steam  is  admitted  to  the  other  1.  p.  cylinder  at  /a,  and  that 
cylinder  is  in  communication  with  the  receiver  and  the  h.  p.  cylinder  until  its  cut-off 


FIG.  152. 
Elementary  Indicator  Cards  from  Three-Cylinder  Compound. 

point  is  reached  at  l\.  There  will  then  be  slight  compression  in  the  h.  p.  cylinder  and 
the  receiver  until  steam  is  admitted  to  the  L  cylinder  at  the  beginning  of  its  next 
stroke.  The  remaining  events  of  the  revolution  are  similar  to  those  already  noticed 
and  will  be  made  clear  by  a  study  of  Fig.  153.  It  will  be  seen  that  there  is  still  read- 
mission  to  the  1.  p.  cylinder  Z,,  but  that  this  does  not  effect  the  form  of  the  card  from 
the  other  1.  p.  cylinder.  With  this  arrangement  of  cranks  and  with  the  same  valve 
adjustment  the  indicator  cards  from  the  two  1.  p.  cylinders  will  be  unlike  for  all  points 
of  cut-off.  There  is  in  fact  but  one  arrangement  of  cranks  for  which  the  distribution 
in  the  1.  p.  cylinders  will  be  the  same,  and  that  is  when  the  1.  p.  cranks  are  both  at 


286 


COMPOUND    LOCOMOTIVES. 


right  angles  with  the  h.  p.,  and  therefore  either  directly  opposite  each  other  or  par- 
allel. Assuming  an  equal  division  of  work  between  the  three  cylinders,  the  most  uni- 
form turning  moment  will  be  obtained  by  placing  the  cranks  at  angles  of  120  degrees 
with  each  other,  but  the  difference  in  the  distribution  in  the  two  1.  p.  cylinders  will 
still  exist. 

An  examination  of  the  crank  positions  for  the  form  of  three-cylinder  engine  hav- 
ing two  h.  p.  cylinders  and  one  1.  p.  cylinder  shows  similar  peculiarities  in  the  distri- 


FIG.  154. 
Elementary  Indicator  Cards  from  Three-Cylinder  Compound. 

bution.  This  will  be  evident  from  Figs.  155  and  156,  which  are  lettered  similarly  to 
Figs.  151  and  153,  H  and  h  representing  the  two  h.  p.  cranks,  which  are  at  right 
angles,  and  /  the  1.  p.  crank,  which  makes  angles  of  135  degrees  with  the  others. 
The  distribution  in  Fig.  155  is  the  same  as  that  in  Fig.  151,  and  that  in  Fig.  156  is  the 
same  as  that  in  Fig.  153.  It  will  be  seen  that  there  is  readmission  to  the  1.  p.  cylinder 
in  both  figures ;  but  at  the  earlier  cut-off  of  T40-  it  is  not  probable  that  the  effect 
on  a  1.  p.  indicator  card  would  be  noticeable.  Placing  the  cranks  at  angles  of  120 
degrees  would,  as  in  the  first  arrangement  of  cylinders,  produce  very  little  change  in 
the  indicator  cards. 


APPENDIX. 


287 


It  is  evident,  from  the  preceding  partial  analysis  of  the  steam  distribution,  that  the 
construction  of  theoretical  indicator  cards  for  three-cylinder  compound  engines  will  be 
considerably  more  difficult  than  for  the  two-cylinder  type,  but  that  the  same  formulas 
and  methods  of  construction  can  be  used.  The  remarks  which  were  made  in  discuss- 
ing two-cylinder  compound  locomotives  in  regard  to  the  effect  of  varying  the  capacity 
of  the  receiver  and  the  results  of  changing  the  points  of  cut-off  are  equally  applicable 
to  three-cylinder  engines.  In  fact,  the  only  differences  are  those  in  the  steam  distri- 
bution, which  have  been  already  discussed,  and  which  depend  upon  the  angles  made 
by  the  three  cranks. 

A  mathematical  discussion  of  the  three-cylinder  type  of  compound  engine,  having 
one  h.  p.  cylinder  and  two  1.  p.  cylinders,  and  with  the  cranks  placed  at  angles  of  120 
degrees  with  each  other,  will  be  found  in  the  appendix  to  "  The  Marine  Steam 
Engine,"  by  R.  Sennett.  The  form  having  two  h.  p.  cylinders  and  one  1.  p.  cylinder 
does  not  appear  to  have  been  used  in  marine  practice,  and  its  use  is  not  to  be  expected, 
inasmuch  as  one  of  the  chief  reasons  for  using  three  cylinders  instead  of  two  is  to 
avoid  excessively  large  1.  p.  cylinders. 


FIG.  155.  F;G.  156. 

Crank  Circles,  Three-Cylinder   Compound, 


-n  attempting  to  determine  the  size  of  cylinders  for  three-cylinder  compound  loco- 
motives, the  best  guide  will  undoubtedly  be  the  results  obtained  with  locomotives  of 
that  lorm  in  practice.  When  such  information  is  not  obtainable,  the  most  satisfactory 
method  will  be  that  advocated  under  similar  circumstances  for  two-cylinder  compound 
engines,  i.  e.,  the  construction  of,  what  were  called  for  convenience,  elementary  indi 
cator  cards,  and  the  alteration  of  these  as  experience  dictates,  to  allow  for  wire-draw 
ing  during  the  opening  and  closing  of  valves,  drop  in  pressure,  etc.  The  proportions 
which  appear  to  have  been  generally  adopted  by  Mr.  Webb  are,  h.  p.  cylinders,  14 
inches  in  diameter;  1.  p.  cylinder  30  inches  in  diameter;  stroke  of  all  pistons,  24 
inches.  The  ratio  of  the  volume  of  the  1.  p.  cylinder  to  that  of  both  h.  p.  cylinders  is 
thus  about  2.  3.  Assuming  a  mean  forward  pressure  of  175  pounds  gauge,  in  the  h.  p. 
cylinders,  and  a  back  pressure  in  the  1.  p.  cylinder  of  3  pounds  above  the  atmospheric 
pressuie  and  an  equal  division  of  work,  we  can  make  an  approximate  estimate  of  the 
maximum  power  of  the  engine  as  follows:  The  area  of  the  1.  p.  piston  is  4.6  times 
that  oi  one  h.  p.  piston,  and,  if  the  work  is  to  be  the  same  in  both,  the  mean  pressure 
in  a  h.  p.  cylinder  must  be  4.6  times  that  in  the  1.  p.  cylinder.  As  the  total  range  of 


288  COMPOUND    LOCOMOTIVES. 

pressure  is  172  pounds,  and  as  the  mean  receiver  pressure  is  approximately  the  same 
as  the  mean  h.  p.  back  pressure  and  the  mean  1.  p.  forward  pressure,  we  have:  4.6 
X  1.  p.  mean  effective  pressure  =  172  —  1.  p.  mean  effective,  whence  1.  p.  mean  effec- 
tive =  172  -+-  5.6  =  30.7  pounds.  The  mean  receiver  pressure  is  then  30.7  +  3  =  33.7 
by  gauge,  and  the  mean  effective  in  the  h.  p.  cylinders  is  175  —  33.7  =  141.3  pounds. 
A  similar  calculation  can,  of  course,  be  made  with  any  assumed  mean  forward  pressure, 
and  this  method  can  also  be  used  for  making  an  approximate  comparison  of  the  maxi- 
mum work  done  in  the  cylinders  of  the  three-cylinder  compound  with  that  in  ordinary 
locomotives.  For  example,  if  the  mean  forward  pressure  in  the  latter  is  150  pounds 
and  the  back  pressure  is  3  pounds  as  before,  the  total  effective  pressure  during 
a  stroke  will  be  2  x  147  x  area  of  one  piston.  To  be  the  equivalent  of  the  compound 
locomotive  this  must  equal  3  X  141.3  X  area  of  one  h.  p.  piston.  This  gives  in  the 
present  case  221.9  square  inches  as  the  piston  area  of  the  simple  engine,  or  in  other 
words  a  simple  engine  having  two  cylinders  about  16.8  inch  in  diameter,  would  be 
equal  in  power,  with  the  assumed  pressures,  to  the  compound  engine  having  cylinders 
14,  14  and  30  niches  in  diameter,  the  stroke  being  the  same  in  all  cylinders. 

The  same  method  can  be  used  to  find  dimensions  for  an  equivalent  three-cylinder 
engine  having  one  h.  p.  and  two  1.  p.  cylinders.  If  the  ratio  of  the  volumes  of  the 
two  1.  p.  cylinders  to  that  of  the  h.  p.  cylinder  is  2.3,  each  1.  p.  cylinder  will  be  1.15 
times  as  large  as  the  h.  p.  Therefore  1.15  X  1.  p.  mean  effective  pressure  =  172  — 
1.  p.  mean  effective,  whence  1.  p.  mean  effective  =  80  pounds.  The  mean  receiver 
pressure  will  be  83  pounds  gauge,  and  the  h.  p.  mean  effective  pressure  will  be  175  — 
83  =  92  pounds.  To  find  the  piston  areas  we  have  92  X  area  of  the  h.  p.  piston  for 
this  engine  =  141.3  X  area  of  a  i4~inch  cylinder,  which  gives  an  area  of  236.3  square 
inches,  17.35  diameter,  for  the  h.  p.  piston,  and  1.15  times  this  or  271.8  square  inches, 
18.6  diameter,  for  each  1.  p.  piston.  An  engine  having  one  h.  p.  cylinder  17.35  inches 
in  diameter  and  two  1.  p.  cylinders  18.6  inches  in  diameter,  is  thus  equivalent  with  the 
assumed  pressures  to  one  having  two  h.  p.  cylinders  14  inches  in  diameter  and  one  1. 
p.  cylinder  30  inches  in  diameter.  The  distribution  of  work  among  the  three  cylinders 
is  considered  in  what  follows. 

Distribution  of  Work. — It  was  shown  in  the  theoretical  discussion  of  the  distribu- 
tion of  work  between  the  cylinders  of  two-cylinder  receiver  compound  locomotives, 
that  with  the  same  points  of  cut-off  in  both  cylinders  and  with  the  ratios  of  cylinder 
volumes  which  are  practicable  in  locomotives,  considerably  more  than  one-half  of  the 
total  work  will  be  done  by  the  1.  p.  cylinder.  It  was  also  demonstrated  that  the  work 
can  be  to  a  great  extent  equalized  by  making  the  cut-off  in  the  h.  p.  earlier  than  that 
in  the  1.  p.  cylinder. 

The  same  process  of  reasoning  can  be  applied  to  the  three-cylinder  type  of  com- 
pound engines,  inasmuch  as  we  may  regard  this  form  as  a  development  of  the  two- 
cylinder  type,  produced  by  substituting  either  two  smaller  h.  p.  cylinders  for  the 
original  h.  p.  cylinder,  or  else  two  smaller  1.  p.  cylinders  for  the  original  single  1.  p. 
cylinder.  It  is,  therefore,  to  be  expected  that,  with  the  same  points  of  cut-off  in  all 
three  cylinders,  considerably  more  than  one-half  of  the  total  work  will  be  done  in  the 
single  1.  p.  cylinder  of  the  Webb  type  of  compound  locomotive,  and  in  the  two  1.  p. 
cylinders  of  the  other  form  of  three-cylinder  compound  locomotive  which,  for  the 
sake  of  brevity,  may  be  called  the  French  type.  We  may  even  go  a  step  further  and. 
say  that,  with  the  ratios  of  cylinder  volumes  which  are  practicable,  the  total  work 
cannot  be  so  divided  that  much  less  than  one-half  of  it  will  be  done  in  the  1.  p. 
cylinders.  This  statement  is  borne  out  by  the  published  indicator  cards  of  the  Webb 
locomotive  and  leads  to  some  interesting  conclusions. 


APPENDIX. 


289 


These  indicator  cards  show  that  the  proportion  of  the  total  work  which  is  done  in 
the  1.  p.  cylinder  is  from  50  to  65  per  cent,  at  various  speeds,  with  the  1.  p.  valve  in 
full  gear.  As  making  the  1.  p.  cut-off  earlier  would  increase  the  proportion  of  work 
done  in  that  cylinder,  it  follows  directly  that  thel.  p.  cylinder's  share  of  the  total  work  is 
at  least  50  per  cent.  As  the  Webb  locomotive  has  no  coupling  rods  between  the  h.  p. 
and  1.  p.  axles,  and  as  the  weight  on  each  pair  of  drivers  is  very  nearly  the  same,  it  is 
evident  that  this  division  of  work  is  the  best  under  the  circumstances.  This  point  and 
others  can  be  well  illustrated  by  a  diagram  of  crank  efforts.  Such  a  diagram  is 
shown  by  Fig.  157,  which  was  constructed  from  indicator  cards  of  a  Webb  locomotive. 
Steam  was  cut  off  at  about  ten  inches  in  the  h.  p.  cylinders,  and  the  1.  p.  admission 


\         B          Q  c          D          AT 

FIG.  157. 
Diagram  of  Turning  Moments,' Three-Cylinder  Compound. 


FIG.  158. 
Diagram  of  Turning  Moments,  Three-Cylinder  Compound. 

•was  at  "  full  gear."  The  speed  is  not  recorded,  but  from  the  form  of  the  h.  p>,  admis- 
sion line  is  evidently  not  great.  The  mean  pressure  is  approximately  81  pounds  in  the 
h.  p.  cylinders,  and  about  34  pounds  in  the  1.  p.  cylinder,  which  is  equivalent  to 
34  X  2.3  =  78.2  pounds  in  the  two  h.  p.  cylinders,  the  work  done  in  the  1.  p.  cylinder 
thus  being  nearly  one-half  of  the  total. 

Referring  to  Fig.  157,  abode  and/^  h  k  I  show  the  variations  in  the  turning 
moments,  or  the  tangential  efforts  on  the  cranks,  of  the  two  h.  p.  pistons,  the  cranks 
being  at  right  angles,  and  the  irregularity  caused  by  the  connecting  rods  being 
neglected.  The  combined  efforts  on  these  two  cranks  is  shown  by  the  curve/"/  (/  /. 
The  variations  in  the  turning  moments  on  the  1.  p.  crank  are  shown  by  a  curve  such 
as  B  CD,  and  if  we  assume  that  the  1.  p.  crank  makes  angles  of  135  degrees  with  the 
h.  p.  cranks,  this  curve  and  that  for  the  other  stroke  D  E  FA  B  will  be  located  as 


2QO 


COMPOUND    LOCOMOTIVES. 


shown  in  the  figure.  Combining  the  h.  p.  and  1.  p.  diagrams  gives  the»full  line  curve 
in  the  figure  which  represents  the  variations  in  the  pulling  power  of  the  locomotive 
during  one  revolution,  as  shown  by  the  indicator  cards,  and  therefore  without  taking 
the  inertia  of  moving  parts  into  consideration.  A  comparison  of  this  full  line  curve 
with  the  curve  of  the  combined  h.  p.  cylinders/"/  q  I  shows  that  the  angles  between 
the  1.  p.  and  the  two  h.  p.  cranks  are  not  of  great  importance.  If  the  1.  p.  crank  were 
moved  back  about  25  degrees,  so  that  the  maximum  moment  for  the  1.  p.  crank  at  C 
would  coincide  with  the  minimum  for  the  combined  h.  p.  cranks  at/,  the  combined 
diagram  for  all  three  cranks  would  be  somewhat  more  uniform,  but  the  difference 
would  not  be  great.  A  diagram  of  crank  efforts  on  the  assumption  of  uniform  steam 
pressures  throughout  the  stroke  in  each  cylinder  shows  similar  peculiarities.  It  has 
been  suggested  that  this  type  of  locomotive  might  be  improved  by  placing  the  cranks 


g          c          p 

FIG.  159. 
Diagram  of  Turning  Moments,  Three-Cylinder  Compound. 


FIG.  i 60. 
Diagram  of  Turning  Moments,  Three-Cylinder  Compound. 

at  angles  of  120  degrees  and  coupling  the  driving  wheels.  The  effect  of  this,  with  the 
steam  distribution  and  division  of  work  used  in  the  construction  of  Fig.  157,  is  shown 
by  Fig.  158,  in  which  the  full  line  curve  shows  the  variations  in  the  combined  rota- 
tive efforts  on  the  three  cranks.  It  will  be  seen  that  the  minimum  turning  moment  is 
greater  than  that  in  Fig.  157  and  the  maximum  is  less,  so  that  there  is  a  more  uniform 
effort  throughout  the  revolution.  The  performance  of  the  locomotive  at  slow  speeds 
would  therefore  be  improved  by  this  arrangement,  but  as  the  speed  is  increased  the 
inertia  of  the  moving  parts  tends  to  diminish  this  apparent  advantage,  so  that  it  is 
doubtful  if  there  would  then  be  any  practical  gain  by  the  introduction  of  coupling- 
rods. 


APPENDIX. 


291 


Turning  now  to  the  French  type  of  three-cylinder  compound  locomotives,  it  will 
be  found  that  an  application  of  the  same  method  of  reasoning  leads  to  very  different 
results.  As  has  been  pointed  out,  the  steam  distribution  is  different  in  the  two  1.  p. 
cylinders,  but  it  is  nevertheless  to  be  expected  that  more  than  one-half  of  the  total 
work  will  be  done  in  the  1.  p.  cylinders  with  the  same  points  of  cut-off  in  all  three 
cylinders.  Also  by  adjusting  the  points  of  cut-off,  the  proportion  of  the  total  work 
done  in  the  h.  p.  cylinder  can  be  decreased.  It  is  therefore  possible  with  this  type  of. 
engine  to  divide  the  total  work  equally  among  the  three  cylinders. 


— 6)r 


\ 


.i 


^°    c   C  )• 
'>>   t-. 

2=3  > 
*  5   g: 

^5      o>- 


In  this  locomotive  the  two  1.  p.  cranks  are  placed  at  right  angles,  and  the  h.  p. 
crank  is  placed  at  135  degrees  with  the  others.  A  diagram  of  crank  efforts  with  this, 
crank  arrangement  and  on  the  basis  of  an  equal  division  of  work,  and  steam  admission 
during  about  %  of  the  stroke,  is  shown  by  Fig.  159.  In  this  figure,-  a  b  c  <£ 
is  the  h.  p.  diagram,  and  e  fg  h  k  and  m  n  o p  q  are  the  1.  p.  diagrams.  The  com- 


2Q2  COMPOUND    LOCOMOTIVES. 

bined  diagram  for  all  three  cranks  is  shown  by  the  full-line  curve.  If  the  cranks  were 
placed  at  angles  of  120  degrees,  the  combined  diagram  would  have  the  form  shown 
by  the  full-line  curve  in  Fig.  160,  from  which  it  is  clear  that  this  disposition  of  cranks 
would  give  a  very  constant  turning  moment. 


J.  Example  of  Modification  of  Elementary  Indicator  Cards  to  Approximate  to 
Actual  Cards  for  Non-Receiver  Compounds,  3. — An  example  of  indicator  cards  con- 
structed in  this  way  is  given  in  Fig.  161,  on  a  much  smaller  scale,  however,  than  is 
advisable  in  practice.  The  assumed  data  in  this  case  is  as  follows :  Initial  press- 
ure, 175  pounds  absolute;  cylinder  ratio,  3;  1.  p.  back-pressure,  17  pounds  absolute; 
cut-off  in  both  cylinders,  0.5;  release  and  compression  in  both  cylinders,  0.78;  volume 
of  h.  p.  clearance,  15  percent.;  volume  of  1.  p.  clearance,  6  per  cent.;  volume  of 
connecting  passages,  0.3  of  h.  p.  cylinder.  The  scale  of  pressures  used  in  the  diagram 
is  80  pounds  to  the  inch.  For  the  benefit  of  those  who  may  wish  to  construct  such 
diagrams  we  will  follow  through  this  case  in  some  detail. 

The  following  symbols  will  be  used  : 

-v  —  volume  swept  by  h.  p.  piston. 

y=     "        "        i.  p. 

^  =        "     of  h.  p.  clearance. 

C=       "     ofl.  p. 

i=        "     of  intermediate  or  connecting  passages. 

The  volumes  occupied  by  the  steam  at  the  several  lettered  points  on  the  diagram 
are,  then, 

At  b,  =  .5  v  +  c  —  .65  v. 

At  d,  =  .78  v  +  c  =  .93  v. 

At  e,  =  .93  v  +  i  =  1.23  v. 

At/,  =  v  +  c  +  I  =  1.45  v. 

Aig,  =  1.45  v  +  C  —  1.63  v. 

At  h,  before  cut-off,  =..$v  +  c  +  i+  C  +  .5  V  =  2.63  v. 

At  h,  in  1.  p.  after  cut-off,  =  .5  V  +  C  =  .56  V. 

At  h,  in  h.  p.  and  passages  after  cut-off  in  1.  p.,  —  .5  v  +  c  +i  —  .95  v. 

At  k,  before  valve  closure,  =  .22  v  +  c  +  i  =  .67  v. 

At  k,  in  h.  p.  after  valve  closure,  =  .22  v  +  c  =  .37  v. 

At  /,  =  .78  V  +   C=  .84  V. 

At  n,  =  .22  V  +  C  =  .28V. 

The  pressure  at  d  and  the  curve  between  b  and  d  may  be  found  by  constructing 
the  curve  through  b  with  B  as  the  origin,  A  B  being  .15  of  A  D;  or  by  calculation  as  the 
pressures  may  be  taken  inversely  as  the  volumes,  whence  pressure  at  d  =  175  x  .65  -+- 
.93  =  122.3  pounds.  The  drop  in  pressure  from  d  to  e  depends  upon  the  pressure  at 
k,  that  in  turn  depends  upon  h,  and  so  upon  g.  The  pressure  at g  depends  upon  that 
at  q  and  at/",  and  so  upon  e.  In  any  case,  there  is  but  one  pressure  at  h  which  will 
fulfil  the  conditions,  and  that  pressure  must  be  determined  by  Calculation.  Assuming 
for  the  moment  that  we  know  the  pressure  at  e  to  be  112.5  pounds,  the  pressure  at/" 
will  be  112.5  X  1.23  -*•  1.45  =  95.4  pounds.  The  pressure  at  g  is  determined  by  the 
mixture  of  the  volume  at  /  at  95.4  pounds  with  the  volume  of  the  1.  p.  clearance  at 
pressure  q.  To  find  the  latter  we  have  pressure  at  q  =  17  x  .28  -»-  .06  =  79.3  pounds. 
Then  pressure  at  g  — 

79.3  X  .18  +  95.4  X  1.45  =  ds> 

.18  +  1.45 


APPENDIX.  2Q3 

The  pressure  at  h  —  93.7  X  1.63-1-  2-63  =  58.1  pounds.  The  pressure  at  k  = 
58.1  X  .95  •+•  .67  =  82.3  pounds.  We  can  now  find  the  pressure  at  e  which  is 

122.3  x  .93  +  82.3  x  .3  =  JI2>5> 

•93  +  -3 
By  combining  these  various  expressions  for  pressures  we  can  readily  form  a  single 

equation  from  which  the  pressure  at  h  can  be  calculated,  which  is,  in  fact,  the  method 
by  which  it  was  determined  in  this  case. 

Having  found  the  pressures  at  e,  g  and  h  by  calculation,  the  various  curves  of  the 
diagrams  can  be  readily  constructed.  For  the  curve  between  e  and  f  a  point  C  is 
used  for  the  origin,  which  is  found  by  laying  off  B  C  equal  to  .3  of  A  D.  The  curve 
h  k  is  constructed  from  the  same  origin.  The  compression  curve  k  u  is  laid  off  from 
B.  To  find  the  origin  for  tke  curve  g  h,  we  proceed  as  follows:  At  g  the  steam 
occupies  the  volume  v  +  c  +  i  +  C,  and  at  h  the  volume  occupied  is  .$v  +  c  +  i  +  C 
+  (.5l/=i.$v),  The  increase  in  volume  is  therefore  equal  to  v,  and  therefore  the 
scale  of  this  part  of  the  diagram  must  be  such  that  the  horizontal  distance  from  g  to  h 
represents  v,  the  volume  of  the  h.  p.  cylinder.  With  this  scale  of  volumes  lay  off  D  K 
=  .06  V  —  .i8v,  K L  =  .yjt  L  N  =  v  and  N  E  =  ,i$v;  then  E  is  the  origin  from  which 
to  construct  the  curve  g  h.  For  the  curves  h  I  and  n  q  the  origin  is  taken  at  H ,  which 
is  found  by  laying  off  D  H  =  .06  of  A  D,  which  for  these  curves  represents  the  volume 
of  the  1.  p.  cylinder. 

This  diagram  illustrates  the  difficulty  of  keeping  the  h.  p.  compression  within 
reasonable  limits. 

K.  Some  Further  Discussion  of  Four-Cylinder  Receiver  Compounds,  124-128. — 
The  elementary  theory  of  four-cylinder  receiver  compound  locomotives  is  essentially 
the  same  as  that  of  two-cylinder  receiver  engines,  and  the  four-cylinder  type  may  be 
regarded,  as  far  as  the  cylinders  are  concerned,  as  formed  from  the  two-cylinder  type 
by  substituting  for  each  cylinder  of  the  latter  two  cylinders  having  a  joint  volume 
equal  to  the  corresponding  single  cylinder.  It  was  shown  in  discussing  two-cylinder 
receiver  engines  that,  in  making  approximate  calculations  to  determine  proportions, 
the  receiver  pressure  may  be  regarded  as  constant,  assuming  that  the  capacity  of  the 
receiver  is  large  compared  with  that  of  a  h.  p.  cylinder.  It  follows  from  this  that  the 
distribution  of  work  in  the  cylinders  is  practically  independent  of  the  angle  between 
the  h.  p.  and  1.  p.  cranks  when  a  large  receiver  is  used.  If  in  a  four-cylinder  engine 
both  h.  p.  cylinders  exhaust  into  one  receiver,  which  is  the  reservoir  from  which  both 
1.  p.  cylinders  are  supplied  with  steam,  the  variations  in  pressure  in  this  receiver 
during  a  revolution  will  presumably  be  less  than  in  a  two-cylinder  engine. 

We  can,  therefore,  in  the  design  of  four-cylinder  elementary  engines,  make 
use  of  formulas  which  are  based  upon  a  constant  receiver  pressure,  proceeding 
at  first  as  if  the  engine  were  to  have  but  two  cylinders.  The  formulas  are  those  which 
are  usually  given  for  two-cylinder  receiver  engines,  and  are  not  of  special  value  in  the 
design  of  two-cylinder  compound  locomotives  on  account  of  the  necessity  of  a  very 
careful  analysis  of  the  steam  distribution  in  that  type  of  locomotive  if  the  possible 
advantages  of  compound  working  are  to  be  realized. 

In  subsequent  formulas  the  letters  have  the  following  meaning: 

v   =  volume  of  h.  p.  cylinder. 
V  =      "         "  1.  p.  cylinder. 

R  =  ratio  of  the  cylinders,  V=  R  v. 

r   =  ratio  of  expansion  in  h.  p.  cylinder. 

r'  —  ratio  of  expansion  in  1.  p.  cylinder. 

p\  —  pressure  in  h.  p.  cylinder  during  admission. 


2Q4  COMPOUND    LOCOMOTIVES. 

pi  =  pressure  in  h.  p.  cylinder  when  exhaust  opens. 
pz  —  mean  measure  in  the  receiver. 
41   =  pressure  in  1.  p.  cylinder  during  admission. 
p\  =  mean  1.  p,  back  pressure. 
All  pressures  are  absolute  pressures. 

Neglecting   the  effects   of   clearance,  the   mean   foi    ard   pressure  in  the  h.  p. 
cylinder  is  : 


The  mean  effective  pressure  is  (pm—pz)  and  the  work  done  in  the  h.  p.  cylinder 
during  a  stroke  is  v  (pm—p*).  Similarly,  the  mean  forward  pressure  in  the  1.  p. 
cylinder  is, 


the  mean  effective  pressure  is  f/'m—  /4Jand  the  work  done  in  the  1.  p.  cylinder  during 
a  stroke  is  V  (p'm  —  -p\  ). 

If  the  work  is  to  be  equally  divided  between  the  two  cylinders,  v  (pm—ps)=  V 
(p'm—ptj. 

On  the  basis  that  volumes  vary  inversely  as  the  pressures,  we  have, 


By  substituting  the  value  for/s  obtained  from  this  equation  in  the  preceding 
one,  and  reducing,  the  following  is  obtained: 

-^(hyp.  log.T-  —  ^)  +  /4=  0.  (4) 

By  means  of  this  equation  the  ratios  of  expansion  in  each  cylinder  (r  and  r'  )  for 
which  the  work  done  in  each  will  be  equal  can  be  determined  for  any  assumed  values 
of  p\  p\  and  R.  If  it  were  required  that  there  should  be  no  drop  in  pressure  at  the 
end  of  the  expansion  in  the  h.  p.  cylinder,  p%  must  equal  ps,  from  which  it  follows 
that  r  must  equal  A*.  It  will  be  found  that  equation  (4)  will  give  impossible  values 
for  r'  for  many  values  of  r.  As  r  becomes  less  or  steam  is  admitted  to  the  h.  p.  cylin- 
der during  a  large  part  of  the  stroke,  r'  will  be  found  to  be  less  than  one  which  is 
manifestly  impossible,  and  shows  that  with  a  late  cut-off  in  the  h.  p.  cylinder  the  work 
cannot  be  equally  divided  between  the  cylinders.  On  the  other  hand,  as  r  is  made 
large,  r'  also  increases  until  it  is  greater  than  R,  which  is  an  impracticable  result,  as 
the  receiver  pressure  would  then  be  higher  than  the  pressure  in  the  h.  p.  cylinder  at 
the  end  of  the  expansion.  For  example,  if  we  take  R  —  2.3,^1  =  190  pounds  abso- 
lute, p\  =  20  pounds  absolute,  and  r  —  1^33,  or  cut-off  at  0.75  of  the  stroke  in  the  h.  p. 
cylinder,  the  equation  reduces  to  hyp.  log.  r'  +  .4348;-  =0.3904  from  which  r'  =  0.97. 
As  steam  is  admitted  during  the  whole  stroke  when  r'  —  i.o,  it  is  clear  that  with  the 
above  proportions  more  than  one-half  of  the  total  work  is  necessarily  done  in  the  1.  p. 
cylinder.  If  r  is  taken  as  equal  to  4,  with  the  other  data  the  same  as  before,  the  value 
of  r'  will  be  found  to  be  3.75,  or  the  1.  p.  cut-off  would  have  to  be  placed  at  i  -+-  3.75 
or  0.267  of  the  stroke.  But  as  there  will  be  no  drop  in  pressure  between  the  cylinders 
when  r'  =  R,  or  when  steam  is  cut-off  in  the  1.  p.  cylinder  at  i  -t-  2.3=0.435  of  the 
stroke,  it  follows  that  to  equalize  the  work  in  the  two  cylinders  at  the  earlier  cut-off  the 
receiver  pressure  would  have  to  be  higher  than  the  pressure  at  the  end  of  the 
expansion  in  the  h.  p.  cylinder. 

The  engineers  of  the  Paris,  Lyons  &  Mediterranean  Railway  have  applied  a  for- 
mula similar  to  the  above  in  the  determination  of  the  proportions  for  a  class  of  four- 
cylinder  compound  locomotives,  and  have  shown  the  proper  relations  existing  between 


APPENDIX. 


295 


the  points  of  cut-off  in  the  h.  p.  and  1.  p.  cylinders  graphically  by  a  diagram  similar 
to  Fig.  162.  This  diagram  is  that  given  by  Mr.  C.  Baudry,  assistant  engineer-in- 
chief  of  motive  power  and  equipment.  Formulas  similar  to  the  above  will  be  found 
discussed  at  greater  length  in  "  Compound  Engines,"  by  Mr.  Mallet.  In  Fig.  162  the 
horizontal  distances  represent  the  points  of  cut-off  in  the  h.  p.  cylinder,  and  the  verti- 
cal distances  represent  the  points  of  cut-off  in  the  1.  p.  cylinder.  The  inclined  lines 
.are  curves  which  represent  the  solution  of  equation  (4)  for  different  values  of  K,  the 
pressures  used  in  the  construction  of  the  diagram  probably  being  213  and  21  pounds. 
For  example,  if  R  —  2.5  when  the  h.  p.  cut-off  is  at  0.4,  the  1.  p.  cut-off  should  be  at 
about  0.5  in  order  to  equalize  the  work.  If  the  ratio  R  —  2,  a  cut-off  at  0.4  in  the 
h.  p.  requires  a  cut-off  at  about  0.58  in  the  1.  p.  cylinder.  For  the  cases  in  which  the 
equation  gives  values  of  r'  which  are  too  small,  the  cut-off  for  the  1.  p.  cylinder  is  fixed 


0.80 


/  /c  / 


0.70 


0.80 


FIG.  162. 
Diagram  Showing  the  Ratios  of  Cut-off  in  High  and  Low-Pressure 

Cylinders  of  Four-Cylinder  Compound. 

at  0.8  or  the  maximum  for  full  gear.  For  instance,  taking  R  =  2,  the  1.  p.  cut-off 
would  remain  at  0.8,  or  full  gear  for  all  values  of  the  h.  p.  cut-off  greater  than  0.58, 
although  more  than  one-half  of  the  work  would  be  done  in  the  1.  p.  cylinder.  The 
other  limit  to  the  application  of  the  formula  is  fixed  by  making  the  earliest  1.  p.  cut- 
off that  at  which  there  will  be  no  drop  in  pressure  between  the  cylinders.  So  that 
finally,  the  relation  between  the  points  of  cut-off  in  the  two  cylinders  is  shown  by 
broken  lines  such  as  a  b  c  d,  for  which  R  —  1.82.  For  example,  if  R  =  2,  the  diagram 
shows  that  the  points  of  cut-off  should  vary  as  follows : 

High-  pressure 10     .20     -30     .40     .50     ,60     .70     .80 

Low-pressure 50     .50     .50     .58     .70     .80     .80     .80 

Three  experimental  types  have  been  constructed  by  the  Paris,  Lyons  &  Mediter- 
ranean Railway.  Fig.  163  shows  the  general  arrangement  of  the  compound  locomo- 
tives intended  for  fast  passenger  service.  The  principal  dimensions  of  these  locomo- 
tives, and  of  the  type  of  simple  locomotive  which  formed  the  basis  for  the  design,  are 
given  in  Table  JJ.  The  table  shows  that  two  compound  locomotives  of  this  and  of 
each  of  the  succeeding  types  have  been  built,  which  differ  only  in  the  number  and 
diameter  of  the  tubes.  It  will  be  seen  that  in  the  type  of  locomotive  illustrated  by  Fig. 
163  all  four  cylinders  are  placed  beneath  the  smoke  box,  with  their  axes  horizontal. 


296 


COMPOUND    LOCOMOTIVES. 


The  two  h.  p.  cylinders  are  between  the  frames  and  are  connected  to  the  lorward 
driving  axle.  The  1.  p  cylinders  are  connected  to  the  rear  driving  axle.  The  axles 
are  so  coupled  that  the  h.  p.  crank  on  each  side  leads  the  1.  p.  crank  *bn  the  same  side 


o: 


T 


l 

i 


fcl 

o 


198°.  The  object  of  this  arrangement  is  to  obtain  as  large  a  value  for  the  minimum 
starting  power  as  possible.  In  Fig.  164  is  shown  the  general  arrangement  of  the  four- 
cylinder  compound  locomotives  for  freight  service.  In  this  locomotive  the  second 
driving  axle  is  connected  to  the  1.  p.  cylinders,  and  the  third  axle  to  the  h.  p.  cylinders. 
The  h.  p.  crank  on  each  side  leads  the  1.  p.  crank  232°  48'.  In  the  corresponding- 


APPENDIX. 


297 


simple  locomotive,  of  which  the  dimensions  are  given  in  the  sixth  column  of  the  table, 
the  rear  axle  is  not  a  driving  axle.  Fig.  165  illustrates  the  arrangement  adopted  for 
locomotives  for  steep  grades.  The  h.  p.  cylinders  are  connected  to  the  second  axle, 


U-r 


and  the  1.  p.  cylinders  to  the  third  axle.     The  h.  p.  cranks  lead  the  adjacent  1.  p. 
cranks,  as  in  the  other  designs,  but  in  this  case  the  angle  is  235°  54'. 

The  Walschaert  valve  gear  is  used  for  all  of  these  locomotives,  and  the  points  of 
cut-off  in  the  h.  p.  and  1.  p.  cylinders  are  adjusted  by  means  of  a  complicated  cam 
arrangement,  designed  to  fulfill  the  requirements  indicated  by  Fig.  162.  The  starting 


2Q8 


COMPOUND    LOCOMOTIVES. 


gear  adopted  for  these  locomotives  consists  of  simply  an  auxiliary  steam  pipe  and 
cock  for  admitting  steam  from  the  boiler  to  the  receiver,  which  is  fitted  with  a  safety 
valve  as  usual. 

For  the  express  locomotive,  Fig.  163,  in  which  the  question  of  the  balancing  of  the 
reciprocating  parts  at  high  speeds  would  be  of  most  importance,  the  angle  selected, 


V 

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APPENDIX. 


299 


198° ,  is  approximately  half  way  between  180°  and  225°.  For  the  freight  locomotive 
the  starting  power  was  apparently  given  greater  weight  in  the  problem ,  the  angles  in 
each  design  being  225°  plus  the  angle  of  inclination  of  the  h.  p.  cylinders 


f  Admisson  of  the  Auxiliary 
Steam  by  the  Low  Pressure  Slide 
$V\de 4 


For  the  phrases  HI,  IT,  and  VH,  via 
The  lines  marked  6'  represent  the 
Steam  as  led  from  the  regulator,  The 
lines  marked  /.• 2  represent  the  Steam 
as  led  from  the  Main  Steam  Pipe . 


Commencement  of  Admisson  of  the  Auzilia 
Steam  by  the  Low  Pressure  Slide . 


Diagram  of  Turning  Moment  at  Driving  Axle 
Compound  Locomotive,  Lindner  System. 
FIG.   166. 

L.  Diagram  of  Turning  Moments  of  a  Lindner  Two-Cylinder  Receiver  Compound, 
103-107. — Fig.  166  shows  an  interesting  diagram  devised  by  Lindner  to*  explain  the 
turning  moment  of  the  Lindner  compound  at  the  driving  axle.  It  applies  to  a  Lind- 
nei  express  engine  in  which  the  h.  p.  crank  leads.  The  boiler  pressure  is  180  pounds 
by  gauge.  The  cylinder  ratio  is  2  2. 

The  path  of  the  crank  and  the  periphery  a  of  the  wheel  are  shown  on  a  scale  of 
•gV  natural  size,  and  the  tangential  forces  transmitted  to  the  periphery  of  the  wheel  are 
shown  as  lines  b  extending  outward  from  the  circumference,  each  millimeter  of  their 
departure  from  a  representing  one  kilogram. 

The  adhesion  circle  c  corresponds  to  a  tractive  force  of  4,000  kilograms  equal  ? 
of  the  adhesion  weight,  while  the  mean  tractive  force  calculated  from  the  dimension? 


3OO  COMPOUND    LOCOMOTIVES. 

of  the  locomotive  according  to  the  formula  z  =  °'^  X ! E  (which  is  the  formula  for 

compound  locomotives)  is  given  at  3,700  kilograms,  d  and  /  representing  the  diameter 
and  stroke  respectively  of  the  h.  p.  cylinder,  p  the  boiler  pressure,  and  D  the  diameter 
of  the  driving  wheel. 

For  the  conditions  of  starting  with  various  positions  of  crank,  four  phases  or 
periods  must  be  considered  for  each  semi-circle. 

(1)  Phases  II-III  and  VI-VII: 

Within  these  phases  the  impulse  takes  place  with  increasing  force  from  the  h.  p. 
piston  alone  without  any  back  pressure,  and  as  in  every  ordinary  locomotive. 

(2)  Phases  IV-V  and  VIII-I: 

The  impulse  takes  place  with  a  force  which  increases  within  these  phases,  and  is 
produced  by  the  1.  p.  cylinder  alone,  with  at  least  the  same  force  as  in  phases  II-III 
and  VI-VII,  while  the  h.  p.  piston  is  at  the  same  time  relieved  by  the  small  equalizing 
channels  in  the  high-pressure  slide, 

(3)  Phases  I-II  and  V-VI : 

The  impulse  is  derived  mainly  from  the  1.  p.  piston  acting  with  a  great  force, 
which,  however,  diminishes  within  the  phases,  while  the  h.  p.  piston  acts  with  small 
but  increasing  force,  and  the  motive  effect  of  these  two  forces  are  combined 

(4)  Phases  III-IV  and  VII-VIII: 

The  impulse,  where  the  auxiliary  steam  is  led  from  the  regulator,  is  derived  solely 
from  the  h.  p.  piston  with  a  great  force,  which  diminishes  somewhat  within  the  phases, 
as  represented  by  the  pressure  line  b  I. 

Where  the  auxiliary  steam  is  led  from  the  main  steam  pipe,  the  1.  p.  piston  also 
works  simultaneously  with  small  but  increasing  force.  The  pressure  which  is  then 
developed  on  the  1.  p.  piston  acts  back  upon  the  h.  p.  piston;  but,  since  the  h.  p. 
crank  is  in  the  most  favorable  position,  the  impulse  is  speedily  given  by  the  h.  p.  pis- 
ton, and  the  motive  effect  does  not  in  any  case  fall  below  the  minimum  values  at 
the  commencement  of  the  phases  indicated  by  (i)  and  (2)  where  only  one  piston  is 
.^working  at  a  time,  but  will  correspond  with  the  pressure  line. 


APPENDIX. 


301 


M.     Some  Tests  of  Compound  Locomotives  in  the  United  States. 
TABLE  II. 

Giving  List  of  some  Tests  of  Compound  Locomotives  which  have  been  made  in  the 
United  States,  and  References. 


Type   of 
Compound. 

Where  Tested. 

Reference. 

Compara- 
tive Value 
of  Test. 

Baltimore  &  Ohio  R.R. 
Mexican  Central   Ry. 
Pennsylvania  R.R  
Lehigh  Valley    R.R 
Mexican  Central  Ry.. 
Lehigh   Valley    R.R. 
Mexican  Central   Ry.  . 
Mexican  Central  Ry   . 
Mexican  National  Ry. 
Mexican  Central   Ry 
West.    Maryland  R.R. 
Old  Colony  R.R  
Illinois  Central   R.R. 
C.,  M.  &  St.  P  
C.,M.  &   St.  P  
Mexican  Central  Ry 
Old  Colony  R.R  
M.    K.   &  T.  R.R.    . 
E.  Tenn.,  Virg.  &  Ga. 
Cin.,  N.  O.&Tex.Pac. 
N.  Y.,  Chic.  &  St.  L.. 
C.,   B.  &  Q  
C.,   B.  &  Q  
C.,  B.   &  Q  
Old  Colony   R.R  
West.  N.  Y.  &  Penn. 
E.  Tenn.,  Virg.  &  Ga. 
E.  Tenn.,  Virg.  &  Ga. 
Union  Elev.,  Brooklyn 
Union  Elev.,  Brooklyn 
Union  Elev.,  Brooklyn 
Southern  Pacific 

R.  R 

Ry. 

Evg. 

.  G.,  il 
i! 

it 

if 

Reviev 

News, 

go  —  Pages  627,  634,  651,  668,  711 
*9i          '       35°,  352,  354  
'       363    
'             '       161 

Fair 
Unimpr't. 

Fair 
Unimpr't. 

Fair 

Unimpr't. 
Fair 

Unimpr't. 
Fair 

Johnstone  
Vauclain  

Johnstone  
Vauclain  &  Dean 
Johnstone  
Johnstone  
Vauclain      
Johnstone  
Vauclain  
Dean    
Vauclain  
Vauclain  
Vauclain    
Johnstone    
Dean 

373    
655 

'       775    
'       812    
'       858    
92                  113    
IQ5    
'       384    
442,  443,  444  
471,472-5,  488,  490-94 
577,   583-4  

'            "       708 

Vauclain  
Pitkin  
Vauclain  
Vauclain  .  .  
Lindner    
Lindner  
Vauclain  
Dean  
Vauclain  
Pitkin  
Pitkin  
Rhode  Island.    .  . 
Rhode  Island.  .   . 
Rhode  Island.     . 
Pitkin 

"       838    
'            "       987 

93         "       162,  163,  170  
"       312    

202-6,  211,    273  

3!3»  3*4,  335-7-8  

'           "       273,  462  
f,  1891  "       657   .... 
Nov.  1890,  Pages  458  
Dec  1891,     '        545-6  

^1891,     "      6-10  
"      556-7  
Feb.     "         "      193  
Jun.  1892,     "      588  
Jun.     "          "      636-9,646-8,657 
Jul.                   ;      6  

Vauclain  
Vauclain  
Vauclain  

Central  R.R.  of  N.  J  .  . 
C.,  M.&St.  P  
C.,M.&St.  P  

302 


31 


'«    a 

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8  £ 

II 

.  ^  a 

h- '    s  -2 
ffi    §  ^ 

ffi   -S.-M 


I! 
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<^  — • 
«   % 


5    K 
^    c 


COMPOUND    LOCOMOTIVES. 

Some  Reported  Savings  by  Compounds  in  the  United  States  : 

!~JSB    I     O      .  ~  —         ••  -         —  - 

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o  g«    |SJjA^ajM  &&^?<««^«  1  >«S  |£|3|^ 


APPENDIX.  303 

O.  Formulas  for  Expansion  Curve. — The  formula  for  the  rectangular  hyper- 
bola is 

p  •  y=  c 

in  which  P  is  the  absolute  pressure  at  any  point  of  the  stroke,  V  the  total  volume 
occupied  by  the  steam,  and  C  a  constant  number  depending  upon  the  pressure  and 
volume  at  cut-off,  or  at  any  point  in  the  stroke  that  is  used  as  the  basis  for  com- 
parison. To  find  C'  take  the  volume  occupied  by  the  steam  at  any  point  of  the  stroke 
and  multiply  it  by  the  absolute  steam  pressure  at  that  point.  To  find  the  pressure  at 
any  point  in  the  stroke  divide  C'  by  the  total  volume  at  that  point. 
The  formula  for  the  adiabatic  expansion  curve  is  approximately 

P.  v.v  =  c- 

In  this  formula  the  letters  have  the  same  signification  as  given  above,  and  the  value  of 
C '  is  found  in  the  same  way.  To  find  the  pressure  at  any  point  divide  C '  by  the  total 
volume  at  that  point  raised  to  V  power.  The  powers  and  roots  are  best  obtained  by 
means  of  logarithms.  To  find  the  loth  power,  take  the  logarithm  of  the  number  and 
multiply  it  by  10,  then  find  the  number  corresponding  to  this  product  in  the  logarith- 
mic table.  To  extract  the  gth  root  of  a  number,  take  the  logarithm  of  the  number  and 
divide  by  9,  and  find  the  number  in  the  logarithmic  table  corresponding  to  the  quo- 
tient. The  adiabatic  curve  of  expansion  is  one  that  takes  into  consideration  the 
amount  of  steam  condensed  in  doing  useful  work  in  the  cylinders,  as  distinguished 
from  that  condensed  by  the  cooling  effect  of  the  cylinder  walls.  The  hyperbola  does 
not  allow  for  condensation,  but  simply  assumes  an  expansion  where  the  pressure 
varies  inversely  as  the  volume  occupied  by  the  steam;  that  is,  when  the  volume  is 
made  twice,  three  or  four  times  as  large,  the  pressures  would  be  %,  %,  and  % 
respectively. 

The  saturation  curve  or  curve  of  equal  steam  weight  can  be  plotted  directly  from 
a  steam  table,  which  gives  the  volume  of  an  equal  weight  of  steam  at  different  abso- 
lute pressures. 

The  curve  of  equal  total  heat  can  be  plotted  from  a  steam  table  which  gives  the 
total  heat  of  an  equal  weight  of  steam  at  different  absolute  pressures. 


P.  Formula  for  Inertia  of  Reciprocating  Parts. — Especially  in  high  speed 
engines  the  inertia  of  the  reciprocating  parts  materially  alters  the  distribution  of  the 
pressure  on  the  crank  pin  during  the  stroke,  although  the  mean  effective  pressure  as 
shown  by  the  indicator  card  for  each  stroke  is  not  changed.  The  only  effect  of  the 
inertia  of  reciprocating  parts  is  to  reduce  the  pressure  on  the  crank  pin  during  the 
first  part  of  the  stroke  and  increase  it  during  the  last  part  of  the  stroke.  During  the 
first  half  of  the  stroke  the  velocity  of  the  reciprocating  parts  is  increased,  and  during 
the  last  half  the  velocity  is  decreased.  In  the  beginning  of  the  stroke  a  portion  of  the 
power  of  the  steam  is  used  to  accelerate  the  reciprocating  parts,  and  in  the  latter  part 
of  the  stroke  the  pressure  on  the  crank  pin  is  increased  by  the  force  required  to  retard 
the  reciprocating  parts. 

The  simple  formula  for  the  inertia  of  the  reciprocating  parts  at  any  angle  of  the 
crank  a  is : 

.ojiwy-  Cosine  a> 

This  formula  does  not  take  into  account  the  obliquity  of  the  connecting  rod,  but 
it  is  quite  near  enough  for  ordinary  analysis  to  omit  this  factor,  particularly  where  the 
connecting  rod  has  considerable  length  in  proportion  to  the  stroke.  The  shorter  the 


304  COMPOUND    LOCOMOTIVES. 

connecting  rod  the  more  necessary  it  is  to  include  the  obliquity  of  the  rod  and  the 
formula  for  such  cases  can  be  found  in  technical  books  on  steam  engines. 

In  the  foregoing  formula  W  is  the  weight  in  pounds  of  the  piston,  piston  rod, 
crosshead  and  part  of  the  connecting  rod.  The  portion  of  the  connecting  rod  to  be 
taken  varies  with  the  design.  For  all  ordinary  analyses  take  1A  of  the  weight  of  the  rod. 

R  -  radius  of  crank  in  feet. 

V '=  equals  the  velocity  of  the  crank  pin  in  its  circular  path  around  the  axle.  This 
velocity  may  be  found  by  multiplying  the  velocity  of  the  train  in  feet  per  seconds  by 
the  stroke  of  the  cylinders  and  dividing  by  the  diameter  of  the  drivers. 

a  is  the  angle  of  the  crank  with  the  horizontal  line  through  the  wheel  centres  at 
the  point  where  it  is  desired  to  find  the  inertia  of  reciprocating  parts.  The  cosine  of 
the  angle  may  be  found  from  any  book  giving  a  table  of  natural  sines  and  cosines  as 
distinguished  from  the  logarithmic  sines  and  cosines. 

The  inertia  of  the  reciprocating  parts  is  to  be  subtracted  from  the  total  steam 
pressure  on  the  piston  for  the  first  half  of  the  stroke  and  added  to  the  total  steam 
pressure  on  the  piston  for  the  last  half  of  the  stroke  in  order  to  find  the  actual  pressure 
on  the  crank  pin. 

The  following  is  an  example  of  the  application  of  this  formula : 

The  weight  of  reciprocating  parts  600  pounds  —  W. 

Velocity  of  train  60  miles  an  hour  or  88  feet  per  second 

Diameter  of  drivers  6  feet. 

Stroke  of  piston  2  feet. 

Total  piston  pressure  38170  pounds. 

Angle  of  crank  with  horizontal  line  through  centres  of  drivers  =35°=  &• 

Position  of  crank  =  first  half  of  stroke. 

Cosine  of  35°=  .819. 

Velocity  of  crank  pin  in  circular  path    = 2  =  29.3  =  V 

6 

The  square  of  29.3  is  858.  =  V12 

The  inertia  of  the  reciprocating  parts  at  an  angle  of  35°  is 

•°3IX600X858-X. 819  =12988   pounds. 

The  actual  pressure  on  the  crank  pin,  when  the  crank  has  moved  35  degrees 
from  the  end  of  the  stroke,  is  the  difference  between  the  total  steam  pressure  and  the 
inertia  of  the  reciprocating  parts,  or — 

38170—12988=25182  pounds. 


APPENDIX. 


305 


Q.  TABLE    L. 

Comparative  Cylinder  Capacities  of  Compound  Locomotives. 


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By  whom  Operated 
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Type  of 
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Remarks. 

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'§ 
fa 

Saxon  State  R.  R. 

Lindner 

25.6 

18.1 

24 

55-6 

29.0 

58.8 

Frgt. 

2  Cylinder. 

44                   44                 44 

44 

23.6 

16.5 

22.1 

75 

32.0 

30.8 

Exp. 

2               " 

44                   44                 44 

" 

25.6 

16.5 

22.1 

75 

32.0 

36.2 

" 

2               " 

C.  B.  &  Q. 

" 

29 

20 

24 

68 

45-8 

38.8 

" 

2               " 

Vladikavkaz 

" 

28 

19^8 

25^ 

47  Y* 

49.9 

50.8 

Frgt} 

2               " 

Pennsylvania  R.  R. 

" 

31 

19-5 

28 

84 

42.0 

46.1 

Exp. 

2               " 

Michigan  Central  R.  R. 

Schenec- 
tady 

29 

12 

24 

68 

48.5 

36.8 

" 

10  Wheel    2  Cyl. 

44                           44                     44 

*4 

29 

20 

24 

74 

49-5 

32.8 

" 

10            "                 " 

Southern  Pacific 

44 

28 

2O 

26 

55 

49-8 

44.6 

Frgt. 

JO            "                   " 

" 

29 

20 

24 

69 

48-3 

36-5 

Exp. 

10            "                   " 

Adirondack  &  St.Lawrn'e 

" 

30 

2O 

26 

57 

57  3 

Frgt. 

Mogul              " 

44                             44                 44 

" 

30 

20 

26 

70 

54-o 

37-3 

Exp. 

10  Wheel 

Pennsylvania  R.  R. 

" 

30 

20 

24 

74 

53  o 

33-2 

" 

10         "             " 

East  Tenn.  Va.  &  Ga. 

" 

29 

20 

24 

Si 

57-8 

41.1 

Frgt. 

Consol.          Cyl. 

Brooklyn  "L" 

Rhode 
Island 

18 

"J* 

16 

42 

15-8 

46.8 

Pass. 

Forney           Cyl. 

N.  Y.,  N.  H.  &  H.  R.  R. 

28 

18 

24 

78 

33-3 

43-6 

Exp. 

8  Wheel         Cyl. 

Minneapolis  &  St.  Louis 

" 

28 

19 

24 

68 

33-5 

49-7 

" 

8       "              ft 

Northern  Adirondack 

" 

28 

19 

26 

62 

46.4 

42.8 

" 

10      "               " 

Fitchburg 

" 

31 

21 

26 

63 

54-0 

44.2 

Frgt. 

Mogul               " 

M.  St.  P.  &  Ste.  Marie. 

<f 

31 

21 

24 

So 

59-i 

47.0 

6t 

Consol.           Cyl. 

N.  Y.,N.  H.  &  H.  R.  R. 

" 

31 

21 

26 

78 

42.0 

46.1 

Exp. 

8  Wheel 

Chicago  M.  &  St.  Paul 

" 

31 

21 

26 

78 

45-° 

43-o 

44      . 

10       "                         " 

Grafton  &  Upton 
Lake  Street  Elevated 

" 

28 

21 

18 

13 

24 
18 

55 
44 

43-o 

21  .O 

47-8 
51.8 

Frgt. 
Pass. 

Mogul  Forney  2" 
8  Wheel         Cyl. 

Northeast  England 

Worsdell 

28 

20 

24 

91^ 

l8.5 

66.6 

Exp. 

2  Drivers,      Cyl. 

Old  Colony  R.  R. 

Dean 

28 

20 

24 

69 

33-2 

49.0 

" 

8  Wheel 

Lehigh  Valley  R.  R. 
C  &  S   S.  R.  T.  R.  R. 

Baldwin 
Brooks 

30 
2O 

28^ 

20 
14 

18 

24 
16 
24 

So 
42 
56 

28.7 

20.0 

38.3 

90.8 
45-9 
52.6 

Frgt. 
Pass. 
Frgt. 

Consol. 
Forney               ' 
10  Wheel 

Lake  Shore  &  Mich.  So. 

Cooke 

27 

jq 

24 

64 

48.5 

34-o 

(C 

10         4<              ' 

Jura-Simplon 

Mallet 

26.4 

17.7 

25.6 

72 

30.6 

48.8 

Exp. 

American          ' 

!! 

Pittsburgh 
Richmond 

29 
29 

19 

26 

72 
54 

47-5 

Si-5 

Frgt. 

8  Wheel            ' 
Mogul              " 

Chesapeake  &  Ohio 
C.  C.  C.  &  St.  L. 

29 

3° 

19 

24 
24 

57 
56 

« 

10  Wheel          " 
10        " 

Illinois  Central  R.  R. 

Rogers 

29 

20 

26 

56 

53-7 

43-8 

" 

Mogul              " 

West  India  Imp.  Co. 

ft 

29 

20 

26 

50 

48.5 

54-3 

" 

10  Wheel 

Jura,  Berne  -Lucerne 

von 
Borries 

25-5 

I8.5 

26 

59 



Exp. 

8             "              2      " 

Pennsylvania  R.  R. 

Webb 

30 

14 

24 

75 

33-4 

51-6 

** 

3  Cylinder. 

London  &  N.  W. 
Chemnitz,  Eng.  Works 

Lindner 

3° 

15 

24 

21 

85 
43^ 

34-7 

44.0 
60.6 

Frgt. 

8  Wheel      3  Cyl. 
4  Cylinder. 

Baltimore  &  Ohio 

Vauclain 

20 

12 

24 

66 

37-8 

46.0 

'* 

8  Wheel      4  Cyl. 

Northern  Pacific 

" 

19 

II 

24 

56 

45-o 

41.2 

" 

Consol.       4    " 

Bahia  Exten.  Brazil 
New  South  Wales 
West.  N.  Y.  &  Penn. 

;; 

IS 

22 
21 

13 

18 
26 
26 

37 
51 

26.5 
61.5 
58-2 

49.6 
48.0 
47-2 

Exp. 
Frgt. 

4  Cylinder. 
10  Wheel    4Cvl. 

10                  4    " 

C.  &  S.  S.  R.  T.  R.  R. 

44 

15 

9 

16 

42 

20.0 

51-8 

Exp. 

Forney        4    " 

Cent.  R.  R.  of  Georgia 

' 

19 

24 

68 

3O.O 

51- 

" 

8  Wheel       4    " 

Cen.  R.  R.  of  New  Jersey 
Columbian  Exposition 

4 

22 
22 

13 

13 

24 
26 

78 
84% 

44.2 

41.6 

40.4 
43-4 

" 

8        "         4    " 
4    " 

44                                   44 

* 

24 

J4 

24 

72 

46.8 

49.6 

'* 

10  Wheel    4    " 

Missouri,  Kansas  &  Texas 

« 

24 

i4 

26 

56 

67.0 

48.0 

Frgt. 

Consol.        4    " 

N.  Y.  L.  E.  &  W. 
Paris,  Lyons  &  Med. 

4  Cylinder 

27 
19.7 

16 

12.2 

28 
24.4 

5° 
78.7 

85-0 
32-5 

58.0 
44-4 

Exp. 

Decapod     4    " 

306 


COMPOUND    LOCOMOTIVES. 


TABLE   L.— Continued. 


i'o  }5  g 

•8 

dj 

(I 

y 

jO 

Ilia 

•A 

,C 

r£ 

> 

> 

2-2  -u<c 

Si 

By  whom  Operated 
or  Built. 

Type  of 
Engine. 

~    C 

o1"1 
£  c 

meter  of  h 
nder.  Inc 

(J5 

"o 

.C 

Q  ^ 

Q  M- 

of  1.  p.  pis 
nent  per 
per  ton  on 
nparative 

>ht  or  Exp 

Remarks. 

55 

•J 

i 

.% 
Q- 

1 

1§1§ 

•3"S.i:< 

I 

Paris,  Lyons  &  Med. 

4  Cylinder 

21.3 

i3-4 

25.6 

59  o 

62.5 

38-0 

Frgt. 

"           "              " 

4         " 

21.3 

14.2 

25-6 

49-5 

63.0 

44-4 

" 

Decauville 

Mallet 
articulated 

II.  O 

7-4 

10.2 

23.6 

12.9 

48.4 

" 

4  Cylinder. 
4 

Herault 

18,1 

12.  I 

20-5 

47-2 

38-5 

44  -o 

«< 

4         " 

Central  Suisse 

" 

21.7 

14.0 

25.2 

65.0 

40.0 

" 

4 

Gothard 
Alsatian  Constructors 
No.  R.  R.  of  France 

Woolf 

22.8 

20.9 
26.0 

15-8 
13-4 
15-0 

25.2 
25    2 
25.6 

48^4 
83.2 
51.2 

93-7 
33-6 
56-9 

34-4 
47.6 
71.2 

Exp. 
Frgt. 

8  Wheel  4  Cyl. 
Tandem  4  Cyl, 

Great  Northern 

Brooks 

22.0  1^.0 

26 

55-° 

65.0 

42.6 

Consol. 

So.  W.  Russia 

Mallet 

19.7 

13.0 

23.6 

79.0 

93-7 

70.9 

Exp. 

Hungarian  State 

Woolf 

19.2 

13.6 

26 

78.5 

30.8 

48.0 

" 

Mexican  Central 

Johnstone 

24  K 

3toi 
3toi 

14.0 
14.0 

24 
24 

48.0 
56-0 

50.0 
52-5 

70.4 
57-6 

Frgt. 

Annular  Cyls. 

Annular  Cyls. 
4  Cyls. 

"        Northern 
Mex.  Cuernavaca  &  Pac. 

24  l/4 

14.0 
14.0 

24 
24 

56-0 
56.0 

5i-5 

59-2 
59-2 

„ 

4  Cylinders 
4 

Mexican  Central 

22^ 

13-0 

24 

48.0 

50.0 

61.0 

" 

4 

"             " 

22^ 

13.0 

24 

56.0 

38.0 

68.8 

Exp. 

4 

" 

22^ 
22^ 

13-0 
13.0 

24 
24 

48.0 
48.0 

50.0 
105.0 

61.0 
58.4 

Frgt. 

Double  Bogie. 

APPENDIX. 


307 


R.  TABLE  C  C. 

Dimensions  of  some  of  the  more  Prominent  Compound  Locomotives  that  have 
been  put  into  Actual  Service,  Chiefly  in  the  United  States. 


Buifafer. 

Patentee. 

•Bid 

&as 
£J^ 

Railroad  Company. 

Baldwin  Locomotive  Works 

Neustadt  Locomotive  Works 
Northern  R'y  of  France 
Brooks'  Locomotive  Works 

Chicago  Burlington  &  Quincy 
Chemnitz  Engine  Works 
Pennsylvania  R.  R.  Shops 
Cooke  Locomotive  Works 
Kolomna  Engine  Works  (Moscow) 
Old  Colony  R.  R. 
Lehigh  Valley  R.  R. 
Alsatian  Constructors 
J.  A.  Maffie,  Munich 

S.M.  Vauclain 

4Cyl. 
4 
4 
4 
4 
4 
4 

2 
2 

3 

2 

Tandem 
2  Cyl. 

2      " 
2       " 
2      " 
2      " 
2      " 

Tandem 
4  Cyl. 
4     " 

2       " 

Tandem 
2  Cyl. 

2      " 
2      " 

4     " 
4     " 
4      ' 
4      ' 
4      ' 

3     " 
3     " 
3     " 

3      ' 
3      ' 
3      ' 
3      ' 

2         ' 
2         ' 

2         ' 
2       " 

C.  &  S.  S.  R.  T.  R.  R. 

Central  R.  R.  of  Ga. 
Central  R.  R.  of  N.  J. 
Columbian  Exposition 

Missouri,  Kan.  &  Tex. 
N.Y..L.  E.  &  W. 
C.  &  S.  S.  R.  T.  R.  R. 
Nothrn  Ry  of  Austria. 
<'         "    "    France. 
Lake  S.  &  Mich.  So. 
Great  Northern. 
C.,  B.  &  Q. 
Royal  Saxon  State. 
Pennsylvania  R.  R. 
Experimental. 
St.  Petersb.  &  Warsaw. 
Old  Colony. 
Lehigh  Valley. 
South  West  Russia. 
St.  Gothard. 
Central  Suisse. 
Jura  Simplon 
So.  R.  R.  of  France. 
Hungarian  State. 
North  Eastern. 
Chesapeake  &  Ohio. 
C.  C.  C.  &  St.  L. 
Mexican  Central. 
"         Northern. 
M.  Cuernavaca  &  Pac. 
Mexican  Central. 

Brooklyn  Union  "L." 
N.  Y.,  N.  H.  &  H. 

C.  Golsdorf 
J.  Player 
A.  Lindner 

'     von  Borries 
F.4W.  Dean 

A.  Mallet 

Alsatian  Constructors 
Hungarian  Ry.  Shops,  Buda-Pesth 
So.  Eastern  Ry,  Gateshead  Shops 
Richmond  Locomotive  Works 

Rhode  Island  Locomotive  Works 

Mexican  Central  R.  R. 
Rogers  Locomotive  Works 
Schenectady  Locomotive  Works 

London  &  North  Western 
Hanover  Machine  Works 

T.  W.  Worsdell 
C.  J.  Mellin 

F.  W.  Johnstone 
C.  H.  Batchellor 

«                  c« 
«               « 

F.(  W.  Johnstone 

Minneap's  &  St.Louis. 
Northern  Adirondack. 
Fitchburg. 
M.  St.  P.  S.  St.  M. 
N.  Y.,  N.  H.  &  H. 
C.  M.  &  St.  P. 
Grafton  &  Upton. 
Lake  St.  "L."  Chicago 
Mexican  Central. 

Illinois  Central. 
West  India  Imp.  Co. 
Southern  Pacific. 
Adirondack  &  St.  L. 

Pennsylvania. 
E.  Tenn.,  Va.  &  Ga. 
Michigan  Central. 
London  &  N.  W. 

Prussian  State, 
jrand  Trunk.     > 
Bengal  &  Nagpur,  Ind. 
Jura,  Berne-  Lucerne. 

A.  J.  Pitkin 
F.  W.  Webb 

A.  v  n  Borries 

Worsdell  &  von  Borries 
A.  von  Borries 

Neilson  &  Co.,  Glasgow 

308 


COMPOUND    LOCOMOTIVES. 
TABLE  C  C.— Continued. 


Reference  No.l 

Type  of  Engine. 

Service  for  which 
Engine  was  built. 

Diameter  and  Stroke 
of   Cylinders.      Inches. 

Diameter 
of  Drivers. 
Inches. 

III 

M.£   3 

|o£ 

T 

Forney 

Elevated 

9  &  15  X  16 

42 

40,000 

2 

8  Wheel 

Passenger 

11%  &  19  X  24 

68 

60,000 

3 

« 

High  Speed  Pass. 

13  &  22  X  24 

78 

88,400 

4 
5 

Special  High  Speed 

"     "     " 

13  &  22   X   26 

14  &  24  X  24 

84^ 
72 

83,140 

93)58o 

6 

Consolidation 

Freight 

14  &  24  X  26 

56 

134,100 

7 

Decapod 

"    . 

16  &  27  X  28 

50 

170,000 

8 
9 

Forney 
6  Wheel 

Elevated 
Freight 

14  &  20  X  16 
i9#  &  29^  X  25 

42 

5oK 

40,000 

10 

ii 

Mogul 
10  Wheel 

Fast  Freight 

17  &  19.7  X  27.6 
18  &  28%  X  24 

1 

90,940 
76,500 

12 

Consolidation 

Freight 

13  &  22   X   26 

55 

130,000 

13 

Mogul 

\\ 

20  &  2Q   X   24 

TT?X     Rr     TRI/£      V      OT 

62 

._!/ 

97,000 

*4 
15 

Double  rJogie 
8  Wheel 

Passenger 

II/8  Oc  lo^/g    A,   21 

19.5  &  31  X  28 

?/* 

84,000 

16 

10         " 

Freight 

19  &  27  X  24 

64 

97,000 

X7 

8      " 

Passenger 

18  &  26  X  25.5 

78 

52,000 

18 
19 

20 

8      " 
Consolidation 
8  Wheel 

Passenger  &  Freight 
Freight 
Passenger 

20  &  28   X   24 
20  &  30  X   24 

13  &  19.7  X  23.6 

69 
50 

79 

66,000 
109,088 
57»3°° 

21 

Articulated 

Freight 

15.8  &  22.8   X   25.2 

48.4 

187,300 

22 

" 

" 

14  &  21.7  X  25.2 

55-1 

130,000 

23 

8  Wheel 

Passenger 

17.7  &  26.4  X  25.6 

72 

61,270 

24 

8      • 

" 

13.4  &  20.9  X  25.2 

83.2 

67,240 

25 

8      ' 

" 

13  &  19.2  X  26 

78-5 

61,508 

26 

8      ' 

« 

20  &  28   X   24 

9i^ 

39,760 

2? 

o      ' 

Freight 

19  &  29  X  24 

57 

89,000 

28 

o      ' 

" 

19  &  30  X  24 

56 

107,100 

29 

o       ' 

" 

14  &  24%  X  24 

56 

103,000 

3° 

o      ' 

" 

14  &  24%  X  24 

56 

103,000 

31 

32 

o      ' 
Double  Bogie 

(i 

14  &  24%  X  24 

13  &  22%    X   24 

56 
48 

103,000 

210,000 

33 

Consolidation 

" 

13  &  22%    X   24 

48 

100,000 

34 

Forney 

Elevated 

11%  &  18  X  16 

42 

31,534 

35 

8  Wheel 

Fast  Passenger 

18  &  28  X  24 

78 

66,52O 

36 

8      " 

Passenger 

19  &  28  X  24 

68 

66,950 

37 

10      " 

" 

19  &  28  X  26 

62 

92,880 

38 

Mogul 

Freight 

21  &  31  X  26 

63 

108,000 

39 

Consolidation 

" 

21  &  31  X  24 

5° 

Il8,22O 

40 

8  Wheel 

Passenger 

21   &  31    X   26 

78 

84,000 

4i 

10      " 

'* 

21   &  31    X   26 

78 

90,000 

42 
43 

Mogul  Forney 
8  Wheel      " 

Freight 
Elevated 

18  &  28  X  24 

13  &  21    X   28 

55 
44 

86,000 
43,000 

44 

10         " 

Passenger 

13  &  22%    X   24 

56 

76,000 

45 

Consolidation 

Freight 

I3  &  22%    X   24 

48 

100,000 

46 

Mogul 

*« 

20  &  29   X   26 

56 

107,300 

47 

10  Wheel 

" 

20  &  29   X   26 

5° 

97,000 

48 

10         " 

Passenger 

20  &  29   X   24 

69 

96,680 

49 

Mogul 

Freight 

20  &  30  X  26 

57 

114,500 

5° 

10  Wheel 

Passenger 

20  &  30  X  26 

70 

108,000 

51 

to         " 

" 

20  &  30   X    24 

74 

106,000 

52 

Consolidation 

Freight 

20  &  29  X   24 

51 

113,500 

53 

10  Wheel 

Passenger 

20  &  29   X   24 

74 

99,000 

54 

6      " 

' 

13  &  26  X  24 

81 

61,264 

55 

6      " 

' 

14  &  30  X  24 

75 

67,200 

56 

6      " 

i 

14  &  30  X  24 

85 

69,440 

8      " 
Side  Tank 

\ 

15  &  30  X  24 
14  &  26  X  24 

ll'A 

69,440 
69,664 

59 

"          " 

' 

14  &  26  X  24 

68% 

65,632 

60 
61 

£.- 

6  Wheel 

Freight 
Passenger 

14  &  30  X  24 

16%  &  23%  X  22% 

r8   Kr    08    tf    V    oA 

62% 
73^ 

64,512 
28,672 

O2 

63 

10  Wheel 

Freight 

IO  OL    20.5    XS    20 

18  &  26  X  26 

51 



64 

8      " 

Passenger 

18.5  &  25.5  X  26 

59 

APPENDIX. 
TABLE  C  C.—  Continued. 


309 


1 
Reference  No.l 

L 

•oo- 

1 

P!" 

C^rT  "" 

1 

^  cr 

Remarks. 

2 

19.0 

17.6 

70.0 
140.44 

554-5 
1567-07 

Mos.  i  to  45. 
'  Nancy  Hanks." 

3 
4 

I 

38.5 
24.6 
18.7 

25.1 

128.23 
152.5 
164.3 

1711  .0 
1478.13 
i793-o 
1768.0 

No.  385. 
'  Columbia. 
'  Columbus." 
Mo.  231. 

7 

89.6 

234-3 

2443-1 

Mos.  800  to  805. 

8 

19.0 

70.0 

555-0 

Mo.  46. 

9 



3ne  of  Five  Engines. 

10 

22.5 



1224.9 

Built  in  1888. 

ii 

23 

112 

1298 

12 
13 
14 

25-3 
27.1 

15 

30.0 

"7 
126.0 

59 
159 

1596 
1506 
930 
1820 

Mo.  324,  Design  of  Mr.  William  Forsyth. 
Meyer-  Lindner  Duplex. 
Class  T,  Design  of  Mr.  Axel  S.  Vogt. 

16 

28.0 

1766.6 

No.  i. 

17 

,0 

26.5 

134.6 

1572 

'  One  of  Nineteen." 

IO 

19 

IQ.  2 

69 



1354 
1658 

Mo.  310. 

20 

20.4 

in.  9 

*3*7 

21 
22 
23 
24 

23-7 
19.4 

21.6 
22 

100.  I 

86  i 
117 

1661.1 

1345-6 
1390.5 
1211.5 

12  Driving  Wheel  "  Goliath." 
8        "            "        Double  Bogie. 
With  "von  Borries"  Starting  Gear. 
Designed  by  Mr.  Du  Bousquet. 

25 

32-3 

129.1 

i45i-5 

Duplex. 

26 

20-7 

123 

1139.0 

No.  1518. 

27 
.28 
29 
30 

27-3 
27-3 

204 
204 

Six  Engines. 
One  Engine. 

2004 
2004 

31 
32 

33 

28.3 

43-4 
21.5 

213  4 
274.0 
148 

2013.4 
2570 
1348 

Three  Engines. 
One  Engine. 

34 

16.5 

56-5 

299-5 

35 

18.5 

138.0 

1229 

36 

23-5 

156.0 

1425 

37 

29.0 

165.5 

1469.5 

38 

27.0 

172 

1493 

39 

25-0 

160 

1700 

40 

34-5 

166.5 

1395-5 

27.0 

204.0 

1788.0 

42 

J7-5 

91.0 

831.0 

43 
44 
45 

17.1 
17.0 
2i-5 

57-6 

122 
I48 

537-5 

1222 
1348 

No.  66,  Altered  from  Simple  Engine. 

46 

26.5 

156 

1516 

47 

26.5 

l64 

l62I 

48 

29-3 

1736.2 

No.  1785. 

49 

No!  15! 

5° 
5i 

26.2 

I4I.7 

1953-2 

No.  1503. 
No.  461. 

52 
53 
54 

1 

28.2 
17.1 
20.5 
20.5 
20.5 

I4I.2 
103.5 
IS9-I 
I59-I 
I2O.6 

1992.6 
1063.7 
1379-6 
I40I-5 
I505-7 

No.  338,  for  "  North  Shore  Limited." 
"  Experiment." 
"  Dreadnaught." 
"Teutonic." 
"  Greater  Britain." 

58 

14.24 

84.8 

993-6 

* 

59 

14.24 

84.8 

993-6 

60 

17.  i 

94-6 

1098.8 

61 

18.7 

78-5 

1047.8 

Built  in  1885. 

62 
63 

22 

104 

1223.0 

Built  in  1887. 

64 

16 

80.5 

1302 

GLOSSARY. 


A. 

Absolute  Pressure. — Gauge  pressure  plus  14.7  pounds. 

Actual  Cut-Off. — The  cut-off  which  includes  a  consideration  of  the  clearance  ; 
the  quotient  of  the  volume  of  the  cylinder  at  the  cut-off  point  including  the  clearance, 
divided  by  the  total  volume  of  the  cylinder  including  the  clearance  on  one  end. 

Actual  Indicator  Cards. — Cards  taken  from  actual  engines  as  distinguished  from 
elementary  cards  drawn  according  to  the  elementary  theory  of  steam  engines. 

Angularity  of  Connecting  Rod. — The  angle  which  the  connecting  rod  makes  with 
the  line  through  the  centre  of  the  cylinder  at  any  point  during  a  revolution. 

Apparent  Cut-Off . — The  cut-off  shown  by  the  indicator  card;  the  cut-off  measured 
from  the  valve  motion ;  a  cut-off  that  does  not  take  into  account  the  clearance  in  the 
cylinders. 

Atmospheric  Line. — The  line  of  no  pressure  as  shown  by  steam  gauge ;  a  line 
drawn  at  14.7  pounds  above  the  line  of  zero  of  absolute  pressures. 

B. 

Back  Pressure. — The  pressure  in  the  cylinders  against  the  piston  on  the  return 
stroke ;  the  pressure  against  which  the  piston  is  moving. 

By-Pass  Valve. — A  valve  which,  when  opened,  permits  the  steam  to  pass  from 
one  end  of  a  cylinder  to  the  other. 

C. 

Clearance. — The  volume  into  which  the  steam  left  in  the  cylinder,  when  the 
exhaust  port  is  shut,  is  compressed;  the  cubical  contents  of  the  space  between  the 
piston,  when  at  the  end  of  its  stroke,  and  the  face  of  the  valve  seat,  including  all  ports 
and  connecting  passages  and  indicator  pipes  if  any. 

Combined  Indicator  Card. — A  diagram  showing  the  cards  from  both  cylinders 
drawn  to  the  same  scale  of  volumes  and  pressures. 

Compression. — Reduction  of  volume  of  the  steam  enclosed  in  the  cylinder  after 
the  exhaust  opening  is  shut;  the  opposite  of  expansion. 

Continuous  Expansion. — Expansion  that  goes  on  without  interruption  as  in  a 
single  expansion  engine;  the  Woolf  type;  the  Vauclain  type;  the  Johnstone  and 
the  DuBousquet;  expansion  without  pause,  as  in  the  case  of  receiver  engines  where 
steam  pauses  in  the  receiver  between  the  two  expansions,  viz.,  one  in  the  h.  p.  and 
one  in  the  1.  p.  cylinder. 

Cut-Off. — The  point  where  steam  is  shut  off  from  admission  to  the  cylinders;  the 
point  of  the  stroke  where  expansion  begins. 

E. 

Elementary  Compound. — A  compound  engine  that  is  assumed  to  give  an 
elementary  indicator  card;  an  engine  assumed  for  the  purpose  of  discussion  and 
illustration. 


312  GLOSSARY. 

Elementary  Indicator  Cards. — Cards  that  do  not  take  into  account  the  losses  of 
pressure  and  volume  in  actual  engines ;  sometimes  called  theoretical  indicator  cards. 

Elementary  Theory. — Limited  theory ;  theory  that  does  not  take  into  considera- 
tion a  majority  of  the  practical  conditions  as  distinguished  from  the  more  perfect  or 
complete  theory. 

Expansion  Curve. — A  curve  which  shows  the  variation  of  pressure  during 
expansion. 

Inertia  of  Reciprocating  Parts. — The  tendency  of  reciprocating  parts  to  remain 
at  rest  or  at  a  constant  velocity ;  the  inertia  is  measured  by  the  force  required  to  get 
the  reciprocating  parts  up  to  speed  or  to  reduce  the  speed  or  to  stop  them. 

Initial  Condensation. — Condensation  which  takes  place  before  cut-off. 

Initial  Pressure. — Pressure  at  the  beginning  of  the  stroke. 

Inside  Clearance — Negative  Lap. — The  opening  of  the  steam  port  to  the  exhaust 
cavity  of  the  valve  when  the  valve  is  at  its  centre  of  motion. 

Intercepting  Valve. — The  valve  which  prevents  the  steam,  admitted  from  the 
boiler  to  the  1.  p.  steam  chest,  from  passing  through  the  receiver  to  the  h.  p.  cylinder. 

L. 

Link  Motion. — All  of  the  distributing  apparatus  such  as  eccentrics,  links,  etc.; 
frequently  intended  to  include  the  valve  and  other  parts  affecting  the  control  of  the 
steam  pressure  in  the  cylinders. 

M. 

Mean  Forward  Pressure. — The  average  pressure  on  the  piston  which  pushes  it 
forward. 

N. 

Negative  Lap. — See  Inside  Clearance. 

Non-Receiver  Engines. — Compound  engines  without  receivers ;  continuous  expan- 
sion engines;  the  Woolf,  the  Vauclain,  the  Johnstone  and  the  DuBousquet. 

O. 

Outside  Lap. — The  distance  which  the  steam  valve  laps  over  the  steam  port  when 
the  valve  is  at  its  centre  of  motion. 

P. 

Potential  of  Pressure.— The  amount  of  pressure ;  the  pressure  above  the 
atmosphere ;  the  intensity  of  pressure ;  used  to  emphasize  the  fact  that  wire-drawing 
causes  a  loss  of  potential  or  force;  strictly,  the  term  is  equivalent  to  pressure. 

R. 

Ratio  of  Cylinders. — Ratio  of  cylinder  volumes,  not  including  clearance;  where 
the  stroke  is  the  same  for  both  cylinders  it  is  the  ratio  of  cylinder  areas. 

Ratio  of  Expansion.— The  ratio  of  the  initial  pressure  to  the  final  pressure  in  the 
cylinder ;  the  quotient  of  the  initial  pressure  divided  by  the  final  pressure ;  sometimes 
taken  as  the  quotient  of  the  final  volume  divided  by  the  volume  at  cut-off,  clearance 
being  included. 

Re- Admission. — Admission  of  steam  the  second  time  during  a  stroke ;  increase  of 
steam  pressure,  during  admission  to  1.  p.  cylinder  caused  by  exhaust  from  h.  p.  cyl- 
inder. 

Receiver  Engine. — A  compound  with  a  receptacle  or  receiver  for  the  steam 
exhausted  from  the  h.  p.  cylinder;  not  a  continuous  expansion  engine. 


GLOSSARY.  313 

Reciprocating  Parts. — The  parts  that  move  forward  and  back  and  do  not  revolve ; 
piston,  piston  rod,  crosshead  and  part  of  connecting  rod. 

Re-Evaporation. — The  evaporation  of  the  initial  condensation ;  the  evaporation  of 
moisture  in  the  steam. 

Release. — The  point  where  the  exhaust  valve  opens ;  the  end  of  expansion. 

S. 

Sequence  of  Cranks. — The  location  of  cranks  with  respect  to  each  other  in  rotation. 
Single  Expansion. — The  expansion  of  steam  in  one  cylinder;  not  compound. 
Steam  Use. — Transforming  the  heat  in  steam  into  mechanical  work ;  utilization  of 
steam  in  cylinders;  method  of  using  steam. 

Super- Heating. — The  heating  of  steam  above  the  temperature  which  it  normally 
has  at  the  same  pressure  in  a  steam  boiler ;  steam  can  only  be  super-heated  when 
separated  from  water. 

T. 

Tandem. — Cylinders  placed  one  in  front  of  the  other,  i,  e.,  placed  in  tandem. 
Total  Expansion. — The  ratio  of  the  initial  pressure  in  the  h.  p.  cylinder  to  the 
final  pressure  in  the  1.  p.  cylinder. 

V. 

Valve  Gear. — All  of  the  valve  motion  which  regulates  the  distribution  of  steam  in 
the  cylinders. 

Valve  Motion. — See  Valve  Gear. 

W. 

Wire-Drawing. — Throttling  steam  through  an  aperture ;  a  reduction  of  pressure 
by  restricting  the  flow  of  steam ;  drawing  through  a  small  opening. 


INDEX. 


NOTE  : — The  large  numbers  given  in  the  body  of  the  book  in  the  midst  of  the  text,  refer  to 
the  numbers  of  the  paragraphs  that  treat  of  the  same,  or  allied,  subjects. 

A. 

Action  of  exhaust 132 

Actual  combined  indicator  cards,  receiver  type 57 

"      ratio  of  expansion 10 

Adiabatic  curve 50 

"            "     formula  for 303 

Adjustments  of  cut-off 105 

"                    "         for  engines  that  run  in  both  directions 105 

"                    "         Mallett's  differential 106 

"  "         numerous  examples  of 111-121 

"                 valve  gear 103 

Advantage  of  large  driving  wheels 21 

Allan  port,  as  affecting  valve  motions 131 

Apparent  cut-off 9 

Austrian  Railways,  Golsdorf,  starting  gear 194 

"                "                  "          two-cylinder  compound  on 194 

Automatic  starting  gears  with  intercepting  valves,  summary  about 249 

"               "          "      without  intercepting  valves,  summary  about 251 

B. 

Back  pressure,  advantage  of  large  nozzles  to  reduce 137 

Back  pressure  as  affected  by  mufflers 258 

"        "        at  high  speed 267 

"         "         effect  of  exhaust  on 134 

"         "             "     on  by  mufflers 253 

"         "  "     of  small  nozzles  on ^34)  136 

"        "         how  it  affects  mean  effective  pressure 138 

"         "         saving  due  to  reduction  of 137 

Baldwin  formula  for  proportions  of  cylinders 76 

"       Locomotive  Works  automatic  intercepting  valve 178 

"       two-cylinder  compound 178 

"                "                "       (Vauclain)   four-cylinder  compound 215 

Batchellor  two-cylinder  compound,  Rhode  Island  Locomotive  Works  202 

Boston  &  Albany  R.  R.,  Dunbar  tandem  four-cylinder  on 211 

Brooks  Locomotive  Works  four-cylinder  tandem 239 

"       (Player)  automatic  intercepting  valve 169 

"                "                "       (Player)  two-cylinder  compounds  169 

"                "                "       tandem,    valve  arrangement 241 

"       two-cylinder  compound,  utility  of 275 

"      tandem  starting  valve 243 

"            "         utility  of 270 

315 


INDEX. 

C. 

Capacity  of  receiver go 

"        various  engines 111-121 

C.  B.  &  Q.  cut-off  adjustment 10g 

two-cylinder  compound  Lindner  system,  design  of  Wm.  Forsyth 185 

valves  for  h.  p.  cylinder i&& 

Clearance 9 

"         calculation  showing  effect  of  on  mean   effective  pressure 283 

"         non-receiver  type  7 

Colvin  intercepting  valve  and  separate  exhaust  for  h.  p.  cylinder 208 

Combined  elementary  indicator  cards,  receiver  type 2 

"         indicator  cards,  area  of 63 

'     non -receiver  type , 57 

'     receiver  type 48 

Combustion  as  affecting  economy 258 

"          effect  on,  by  exhaust 256 

rate  of,  as  affecting  cost  of  repairs 263 

"          saving  by  better 254 

"                  "        more  complete 256 

"         reduction  of  rate  of 356 

Compound  best  adapted  for  a  given  service 269 

"          cylinder  capacities  of  various 305 

"          dimensions  of  various 305, 307-309 

"          economy  of,  in  United  States 302 

"          future  of,  opinion   of  Axel  S.  Vogt 262 

"          how  to  run   when  disabled  on  one  side 279 

"          miscellaneous  designs  of 248 

"          selection  of  a  suitable  design   277 

"          tests  of ,  in  U.  S 301-302 

"          utility  in  case  of  accident  to  machinery 279 

Compression !  T 

"           as   affected  by  driving  wheels 140 

valve  motion 123 

"           at  high  speed 267 

"            curve,  difference  between  actual  and  hyperbola 16 

"           curve,  modification  of 13 

"            effect   of  long  travel  and  wide  outside  lap  of  valve  on 121 

how   affected   by  back  pressure 138 

"            non -receiver  type   * 7 

"  various  engines  111-121 

Condensation,  as  shown  by  indicator  cards 98 

"                     "                 "             "      example  of 102 


causes  of 


97 


"            how  to  prevent 104 

"            in  receiver 54 

saving  by  reduction  of 254>  256 

Continuous  expansion  or  Woolf  type 2 

"         "     four-cylinder  211 

Cooke  Locomotive  Works  starting  gear 192 

"        two-cylinder  compound 192 

"          utility  of 275 

Cost  of  repairs  as  affected  by  rate  of  combustion 263 

Counterbalancing 139 

as  affected  by  driving  wheels • 140 

inertia  of  reciprocating  parts 140 

"                         "               large  drivers 140 


INDEX.  317 

Counterbalancing  as  affected  by  reciprocating  parts 140 

"              distribution  of  centrifugal  pressure  over  track 144 

effect  on,  of  inertia  of  reciprocating  parts 140 

formula  for  inertia  of  reciprocating  parts 303 

marine  practice  in 140 

reduction  of,  by  decrease  of  reciprocating  parts 144 

"               reduction  of,  by  increase  of  diameter  of  drivers 144 

variation  of  centrifugal  pressure  on  track  during  a  revolution 144 

Crank  axles,  disadvantage  of 269 

Cranks,  sequence  of *  83 

Crosshead,  Vauclain 219 

Crossheads  and  guides,  arrangement  of  in  Vauclain  compound 218 

"           and  pistons,  arrangement  of,  in  Johnstone  compound 234 

Curve  of  equal  steam  weights 50 

"         expansion,  construction  of 10 

"         reference,   for  combined  cards,  non-receiver  type 63 

"         saturation 50 

Cut-off,  actual 9 

"        adjustments 105 

as  affected  by  cylinder  ratio  and  receiver  capacity 106 

C.  B.  &Q 108 

for  engines  that  run  in  both  directions   105 

"             Heintzelman's,  on  Southern  Pacific 109 

Mallet's  differential 106 

"                    "         early  form 106 

numerous  examples  of 111-121 

Rogers  Locomotive  Works , 1 1 1 

"         apparent 9 

"         diagram   of,    in   four- cylinder  receiver  types 294 

"         difference  between  actual  and  apparent 25 

"         effect   of  changing  in  elementary  engine 38 

"         P.  R.  R.  two-cylinder  compound 191 

Cylinder  apparatus,  cost  of  repairs  to 263 

"         Baldwin  formula  for  proportions  of 76 

"         capacities  of  various  Compounds 305 

"         cocks  and  starting  gear,  recent  form  of  Vauclain 226 

"          Vauclain 217,  222,  224 

' '         condensation    in 97 

"         effect  of  large,   on   single   expansion  engines  256 

"         limit  of  oiling 255 

"         Mallet   double  1.  p '. 201 

"         power,  per  cent,  of  consumed  by  locomotives  and  tenders 20 

"         ratio,  effect  of  on  cut-off   adjustments 106 

"         ratio  of,  affected  by  maximum  width  of  locomotive 72 

"         as  commonly  used 73 

"         elementary  formula   for 72 

"         four-cylinder  compound 73 

"         two- cylinder    compound 73 

"         ratios,  Mallet's  rule  for 73 

"     two-cylinder  compounds,  Mallet  and   Brunner 78 

"     von  Berries'  rule  for 73 

volumes,   ratio  of,  to  the  work  to  be  done 76,  304-5 

"        von  Berries'  formula  for  proportions  of 77 

D. 

Dean  automatic  intercepting  valve !6e 

"           "                    "                 "     modification  of .  t6<; 


INDEX. 

Dean   two-cylinder  compound 165 

"           utility  of 275 

Decrease  of  hauling  power  as  speed  increases 22-3 

"  mean  effective  pressure  as   speed  increases 19,  22 

Diagram  of  rotative  effort - 88 

Difference  between  actual  and   apparent  cut-off 25 

"  "  "         "      elementary  mean  effective  pressures 26, 29. 

"       compression  curve  and  an  hyperbola 16 

"       work  and  that  shown  by  elementary   indicator  cards 31 

"       calculated  and  actual  mean  effective  pressure 18 

"         in  ratio  of  expansion  when  calculated  by  different  rules  in  common  use 70 

Dimensions     of  various     compounds 305  ,  307-309 

Distributing  valve,  Mallet 200 

Distribution  of  power ,  two-cylinder  compounds 74 

"                 pressure   on  pistons,  Vauclain  compound 228 

steam  in  single   expansion  locomotives 129 

of  work  of   three -cylinder,  three-crank   types 288 

Double  1.  p.    cylinder,  Mallet,  Lapage 73,  78,  79 

Draw  bar  pull,  effect  on  by  decrease  of  mean  effective  pressure 19 

Driving  wheels,  advantage  of  large 21 

"        effect  of  on  compression 140 

"        "       piston  speed 140 

"        "      counterbalancing 140 

"    on  wire-drawing 140 

"       as  affecting  counterbalancing 140 

"       reduction  of  counterbalancing  by  increase  of  diameter  of 144 

Drop   in  pressure  between    boiler  and    steam   chest 133,  135 

' '           during  admission  to  h.  p.  cyl .    33 

"             "           in  receiver 3,  282 

Du  Bousquet,  four-cylinder  tandem  compound  Northern  Railway  of  France 211 

"             tandem,  indicator  cards  from 213 

"                  "         utility  of 270 

Dunbar  four-cylinder  tandem  compound,  Boston  &   Albany  211 

Duplex  compound,  Meyer-Lindner 185 

E. 

Economy  as  affected  by  price  of  fuel 258 

"  "  rate  of  combustion 259 

"  of  compounds  in  U.  S 301,  302 

"  elevated  service 258 

"  in  fast  service 257 

"  in  freight  service 257 

"  in  suburban  service 257 

"  method  of  operation  to  gain 264 

"  possibilities  of 254 

' '  reasons  for 254 

"  when  compounds  are  compared  with  overworked  single  expansion  engines 260 

Effect  of  changing  cut-off  in  elementary  engine 38 

"  "  "  on  receiver  pressure * 40 

"  speed  on  shape  of  indicator  cards 35 

"  on  draw-bar  pull  of  decrease  of  mean  effective  pressure 19 

Elementary  indicator  cards i 

' '  receiver  type • 2 

"  of  Woolf  or  continuous  expansion  type 5 

Elementary  indicator  cards,  modification  of 292 

"  "  "  non- receiver  type 4 


INDEX.  319 

Elevated  and  suburban  service,  mufflers  for  exhaust 136 

"            "          saving  in 258 

Equalization   of  power,  ratio  of  cylinders   as  affecting 74 

"          non-receiver  compounds 75 

work  in  h.  p.  and  1.  p.  cyls.,  conclusions 44 

of  a  non-receiver  compound 43 

"             of  a  receiver  compound 42 

Evaporation  per  pound  of  coal , 259 

Exhaust,  action  of 132 

"           apparatus,  location  of 256 

'•           effect  of,  on  back  pressure 135 

"         on    combustion 256 

"         on  fire 135 

"           independent  for  h.  p.  cylinder 85 

"           mufflers  in  elevated  and  suburban  service 136 

"           nozzles,  effect  of  small,  on  back  pressure 134 

"           saving  due  to  action  of 136 

Expansion,  actual  ratio  of 10 

as  affected  by  size  of  ports 255 

construction  of  curve  of 10 

curve,  hyperbola 103 

curves,  formula  for 303 

curve,  point  from  which   it  is  to  be  drawn 63 

difference  in  ratio  of,  when  estimated  by  different  rules 70 

"            effect  of  steam  passages  on 255 

"             final  pressure 281 

limit  of,  in  single  expansion  cylinders 256 

saving  by  greater 255 

"      due  to  greater 254 

F. 

Formula  for  compression 13 

"         for  mean  effective  pressure 17 

"         for  receiver  pressures 47 

Forsyth,  Wm.,  design  of  Lindner  system  on  C.,  B.  &  Q.  R.  R 185 

Four-cylinder  compound  cylinder  capacity  compared  to  two-cylinder 275 

"                    "          Johnstone,  arrangement  of  pistons  and  crossheads 234 

"           starting  gears  for,  summary  about 252 

"           (Vauclain),  Baldwin  Locomotive  Works 215 

continuous  expansion  or  Woolf  type 211 

"             four-crank  compounds,  with  receivers,  starting  of 86 

four-crank  types,  utility  of 269 

"             non-receiver  compounds 211 

non-tandem,  two-crank  types,  utility  of 272 

receiver  types,  diagram  of  cut-offs  in ,  .  294 

"     Paris,  Lyons  &  Mediterranean 294-9 

theoretical  discussion  of 293 

tandem,  Brooks  Locomotive  Works 239 

compound  on  the  Northern  Railway  of  France,  Du  Bousquet 211 

on  Hungarian   State  Railways 235 

on  South  Western  Railway  of  Russia 237 

receiver  compounds 235 

"         compound,  hauling  power  of 95 

two-crank  types,  utility  of 270 

two-crank,  hauling  power  of 95 


32O  INDEX. 

Four-cylinder  two-crank  receiver  and  non-receiver  compounds,  starting  of 85 

Freight  service,  economy  in 257 

"        saving  in 257 

Fuel,  effect  on  train  expenses 258 

"     comparison  of  American  and  foreign 260 

"     price  of,  as  affecting  economy 258 

"       effect  on  saving  due  to  compounding 258 

"     price  of,  as  affecting  train  expenses 258 

"     relative  value  of  different  kinds 259 

"     used  per  sq.  ft.  of  grate  per  hour 259 


German  state  railroads,  piston  valves  on 122 

Golsdorf  (Austrian)  starting  gear 194 

two-cylinder  compound 194 

"         two-cylinder  compound,  utility  of 275 

Graphical  representation  of  hauling  power 87 

Grate  area,  limit  of '. 258 

"      fuel  used  per  sq.  ft.  per  hour 259 

H. 

Hauling  power,  decrease  of  as  speed  increases 22-3 

"       formula  for 283 

"      graphical  representation  of 87 

variation  of  with  four-cylinder  two-crank  compounds 95 

Heintzelman  cut-off  adjustment  on  Southern  Pacific 109 

Hungarian  four-cylinder  tandem,  utility  of 270 

"            State  Railways,  four -cylinder  tandem  on 235 

Hyperbola  as  an  expansion  curve 49,  103 

"          point  from  which  drawn 51 

"          formula  for 303 

I. 

Ideal  combined  indicator  cards 55 

Increase  of  pressure  in  receiver 4 

Independent  exhaust  for  h.  p.  cylinder  on  Southern  Pacific  R.  R 164 

Indicator  cards,  actual,  total  expansion  from 69 

"            "      combined,  reference  curves 65 

"      effect  of  speed  on  shape  of 35 

"      elementary i 

"            "             "             receiver  type 2 

"            "            "             total  expansion  from 69 

"      example  of  small  drop  in  pressure  between  boiler  and  steam  chest 133-134 

"      examples  showing  leakage 102 

"      from  Du  Bousquet  tandem 213 

"         "      non-receiver  type  combined 57 

"         "      three -cylinder  three-crank  types 285 

"      ideal,  combined 55 

"      in  practice 32 

"      limitations  of  combined 53 

"       losses  shown  by  combined  cards  from  non-receiver  type 61 

"            "      Mallet  tandem  Southwestern  Railway  of  Russia 238 

"      method  of  combining  non-receiver  type 58 

"      modification  of  elementary 292 

"            "      non-receiver  type,  correct  area  of  combined 63 


INDEX.  321 

Indicator  cards  non-receiver  type,  curve  of  reference 63 

"         purposes  of  combining 61 

"      point  to  draw  reference  curve  from 63 

"      receiver  type,  actual  combined 57 

"           combined % 48 

"      reference  curve  on  combined 55 

"             "      showing  advantage  of  large  'steam  passages 134 

"  "        condensation 98,102 

"                          "        leakage  of  valves 98 

"        re -evaporation 102 

"                           "        steam  distribution  by  reverse  lever 267 

"             "            "        steam  distribution  by  use  of  throttle 265 

"      variations  in 35 

"             "      showing  weight  of  steam  per  stroke 98 

Inertia  of  reciprocating  parts   as  affecting  counterbalancing 140 

"                                      "      formula  for 303 

"      Vauclain  compound - 228 

Inside  lap  and  negative  lap,  effect  of 124 

"        "   of  valve 122 

"       negative  lap,  various  engines 111-121 

Intercepting  valve  and  separate  exhaust  for  h.  p.  cylinder  (Colvin)   Pittsburgh  Loco.  Wks.  208 

"            "                "                    "                    "                 Rhode  Island  Locomotive  Works  202 

"                    "                    "                  Southern  Pacific 164 

"                  two-cylinder   receiver  compound  146 

"                                                                                             von  Borries' 209 

'*        and  separate  exhaust  h.   p.   cylinder   (Mellin)  Richmond  Locomotive 

Works 205 

"        automatic,  Baldwin  Locomotive  Works 178 

"             "                "           Rogers  Locomotive  Works 171 

"                               "           von   Borries,  early  form 149 

"         Dean  automatic 165 

"             "         Mallet 198 

"         modification  of  Dean  automatic   165 

"             "         modification  of  Pitkin  automatic  Schenectady  Locomotive  Works 160 


Worsdell  automatic 


155 


Pitkin  automatic,  Schenectady  Locomotive  Works 157 

"         Player  automatic,  Brooks  Locomotive  Works 169 

"             "         recent  changes  in  von  Borries'  automatic 153 

"            "         von  Borries'  automatic 147 

ini889 J47 

"          modification  of 152 

automatic,  on  Jura,  Berne-Lucerne 150 

non-  automatic 153 

"        Worsdell  automatic !53 

"     early  form  of 154 

"         automatic  starting  gears,  summary  about 249 

"         non -automatic,  summary  about 251 

J- 

Johnstone  four-cylinder  compound,  arrangement  of  pistons  and  crossheads 234 

OH  Mexican  Central 233 

"                "                       "             utility  of 272 

L. 

Lapage  double  J.  p.  cylinder 78 

Leakage  as  shown  by  indicator  cards,  example  of IO2 

"      of  valves,  as  shown  by  indicator  cards 08 


322  INDEX. 

Limitations  of  combined  indicator  cards 53 

Lindner  automatic  starting  gear 181 

"       modification  of 184 

"                              *         "       on  Saxon  State  R.  R 185 

"         diagram  of  turning  moment  of  two-cylinder  compounds 299 

"         Meyer  duplex  compound 185 

"         starting  power 94 

"         two-cylinder  on  C.,  B.  &  Q.,  design  of  Wm.  Forsyth 185 

on  P.  R.  R.  design  of  Axel  S.  Vogt 188 

"         two-cylinder  compound 181 

"         utility  of 275 

Locomotive  test  at  Purdue  University. 68 

Loss  due  to  drop  of  receiver  pressure 47 

"           "     use  of   mufflers 136 

"           "     wire-drawing 132 

"     in  pressure,  non- receiver   type 6 

Losses  shown  by  combined  cards  of  non-receiver  type 61 

Low-pressure  cylinder,  re-admission  in 34 

M. 

Mallet,  as  originator   of  practical   compounds 146 

"       differential   cut-off  adjustment *. 106 

"       distributing   valve 200 

"       double  1.  p.  cylinder 73,  201 

"       early  form  of  cut-off  adjustment 106 

"       intercepting  valve 198 

"       preliminary  work  of 201 

"       rule  for  ratios  of  cylinders. . 73 

"       starting    valve 197 

"       system,  early   form  of 199 

"            "        on  Western   Switzerland  Railway 196 

"            "        starting  power  of 90 

"            "        with  separate  exhaust  for  h.  p.  cylinder 196 

"      tandem  on  Southwestern  Railway  of  Russia,  indicator  cards  from 238 

"             "       piston  for 237 

"             "       utility  of 270 

"       two-cylinder   compound 196 

"                                                    utility  of 275 

Mean  effective  pressure  at  high  speed 267 

"          decrease  of  as  speed  increases 19,  22 

"          difference    between  actual  and  elementary  in  h.  p.  cylinder 26 

"             "             "                     "             "             "                          "                 1.  p.  cylinder 29 

"             "                                   "             "           calculated  and  actual 18 

"             "             "          equivalent  in  one  cylinder 282 

"             "             "          example  of  calculation  of 281 

"             "             "                "                    "               including  clearance 283 

"             "             "         formula  for 17 

"          how   it   affects  back  pressure 138 

Mellin   automatic   intercepting  valve   and   separate  exhaust  for  h.  p.   cylinder,  Richmond 

Locomotive  Works 205 

"        two-cylinder  compound,  Richmond  Locomotive  W'orks 205 

Method  of   combining  cards  of  non-receiver  type 58 

"           operation,   necessity  for  wide-open  throttle 132 

Mexican  Central  Ry.,  Johnstone  four-cylinder  compound  on 233 

Meyer-Lindner  duplex  compound 185 

Miscellaneous  designs  that  have  not   been  put  in  service 248 


INDEX.  323 

Modification  of  compression  curve '. 13 

Mufflers,  effect  on  back  pressure.. ..  .-.. 25% 

"         exhaust,   in  elevated  and  suburban  service t 136 

"         loss  due  to  use  of 136 

N. 

Negative  lap,  effect  of  at  low  speeds 125, 127-128 

conclusion  about 130 

example  of  small  effect  of 129 

inside  lap,  effect   of 124 

"              large  on  P.  R.  R.  compound 130 

of  valve,  P.  R.  R.  two-cylinder  compound 191 

various  engines 111-121 

Non-automatic  intercepting  valves,  summary  about , 251 

starting  gears,  starting   power  of go 

"                            "              summary  about 251 

Non-receiver  compounds,  ratio  of  cylinders  and  equalization  of  power  in 75: 

type,  clearance 7 

"      compression 7 

"•     loss  in  pressure 6 

"      of  elementary  indicator  cards 4 

Northern  Railway  of  France,  four-cylinder   tandem  on 211 

"         three -cylinder  compound 246 

"       valve  gear 247 

Nozzle,  advantage  of  large  on  back    pressure ^y 

exhaust,  effect  of  small  on  back  pressure 134,  13(3 

O. 

Oiling  of  cylinders,  limit  of 2eg 

Operation,  method  of,  to  gain  economy 2g , 

'•'         of  compounds  when  disabled  on  one  side 270 

"        of  locomotives,  proper,  saving  effected  by 264 

Outside  lap,  effect  on  valve   motion  of  increasing I2, 

"          and   long  valve  travel  on  Philadelphia   &  Reading  R.  R I24,  I26 

"          for  various  engines ' 111-121 

"         of  valve I22 

of  valve,   P.  R.   R.    two-cylinder  compound 1gI 

P. 

Paris,  Lyons  &  Mediterranean,  four-cylinder  receiver  types 294-299 

Patents,  variety  of j.  g 

Penn.  R.  R.,  piston  valves igo 

P.  R.  R.  two-cylinder  compound,  Lindner  system,  design  of  Axel  S.  Vogt jgg 

Per  cent,  of  total   cylinder  power  consumed  by  locomotives  and  tenders 2O 

Philadelphia  &  Reading  R.  R.  valve  motions I2.    I2g 

Piston  for  Mallet  tandem 

"       speed,  effect  of  large  drivers  on o 

"       valve  bushing,  on  Vauclain  compound 2I_ 

"      valve,  Vauclain 2l6j  2I? 

122 

'     for  P.  R.  R.  two-cylinder  compound Igo 

"     on  German   State  Railroads I2_ 

Pistons  and  crossheads,  Johnstone  four  -cylinder  type 2,  . 

"       distribution  of  pressure  on,  Vauclain  compound 22g 


324  INDEX. 

Pitkin  automatic  intercepting  valve 157 

"      modification  of  automatic  intercepting  valve 160 

"       two-cylinder  compound 157 

Pittsburgh    Locomotive    Works    (Colvin)     intercepting  valve     and    separate    exhaust    for 

h.  p.  cylinder 208 

Locomotive  Works    (Colvin)  two -cylinder  compound 208 

"            two-cylinder  compound,  utility  of 275 

Player  automatic  intercepting  valve,  Brooks  Locomotive  Works 169 

"      two-cylinder  compound,  Brooks  Locomotive  Works 169 

Point  from  which  to  draw  hyperbola 51 

Port  openings,  P.  R.  R.  two-cylinder  compound 191 

"  "  various  engines in -121 

Ports,  dimensions  of 77 

"       effect  of  on  expansion 255 

Power,  distribution  of,  two -cylinder  compounds 74 

"        starting  with  close-coupled  cars   and  free  slack 84 

Pressure,  drop   in,   during  admission  to   h.  p.  cylinder 33 

"        in  receiver 40,  44 

"          effect  of  a  change  of  cut-off  on 40 

Proportions  of  cylinders,  Baldwin  formula 76 

"          von  Borries'  rule  for 77 

Purdue  University,  engine  test  at 68 


R. 

Radiation,  as  prevented  on  Old  Colony  engine 98 

"          effect  of 97 

"          need  of  covering  hot  surfaces 97 

"          neglect  of  consideration  of .' ; 97 

"           saving  by  reduction  of 256 

Rate  of  combustion,  effect   on  economy 259 

Ratio  of  cylinders  and  equalization  of  power  in  non- receiver  compounds 75 

"                "          as  affected  by   maximum  width  of  locomotive 72 

"                "          as  affecting  equalization  of  power  in  two-cylinder  receiver  compounds.  ...  74 

"                "          commonly  used 73 

"                "          elementary  formulas  for 72 

"                "          four-cylinder  compound 73 

"                "          Mallet's  rule  for 73 

"                "          two-cylinder  compound 73 

"                "          volumes  to  the  work  to   be  done 76 

"                "          von   Borries'  rule   for 73 

Re-admission  in   1.  p.  cylinder 34 

Receiver,  calculation  for  pressure  in 281 

"         capacity 80 

"              "       effect  of  on  cut-off  adjustment 106 

"              "        P.  R.  R.  two-cylinder  compound 192 

"  "        various  engines 111-121 

"        condensation   in 54 

"        drop  in  pressure  in 3»  2^2 

"         increase  of    " 4 

"        pressure 4°>  44 

"            "        elementary  engine,  effect  of  a  change  of  cut-off  in 40 

"         pressures,  formula  for 47 

"            "             loss  due  to  drop  of 47 

"        re-evaporation  in 54>  82 

"        re-heating  in 276 


INDEX.  325 


Receiver  super-heating  in 54 

"         type  of  elementary  indicator  cards 2 

"         volume  of,  von  Borries'  rule 77 

Reciprocating  parts,  American  and   foreign _  ^n 

"  "as  affecting  counterbalancing 140,  144 

"      comparative  effect  of  American  and  foreign 143 

"      effect  of  heavy I3g 

"                "      example  of  reduction  of 140 

"      formula  for   inertia  of 303 

"      heavier  for  compounds I3g 

"      inertia  of,  Vauclain  compound 228 

"      necessity  for  reduction  of  weight  of I3g 

"      reduction  of  counterbalancing  by  decrease  of 144 

"      weight  of _  !39 

Re -evaporation  as  shown  by  indicator  cards 98 

"     example  of 98,  102 

during  expansion,  cause  of IO3 

in  receiver 54,82 

of   condensed  steam  in  cylinders, 52,  66. 

Reference  curve  on  combined  indicator  cards 55 

rectangular  hyperbola 49 

Re-heating  and  steam  jackets 80 

in  receiver 276 

Repairs,  cost  of 259,  262 

"     as  effected  by  boiler. . 263 

"     as  compared  to  savings 264 

"     to  cylinder  apparatus 263 

Reverse  lever,  indicator  cards,  showing  steam  distribution  by 267 

Rhode  Island  Locomotive  Works  (Batchellor)  two-cylinder  compound 202 

"         intercepting  valve  and  separate  exhaust  for h.  p.  cylinder..  202 

two-cylinder  compound,  claims  for 205 

utility  of 275 

Richmond  Locomotive  Works  (Mellin)   automatic  intercepting  valve  and  separate  exhaust 

for  h.  p.  cylinder 205 

"   (Mellin)    two-cylinder  compound 205 

"                 "  two-cylinder  compound,  utility  of 275 

Rogers  Locomotive  Works  automatic  intercepting  valve 171 

"         cut-off  adjustment I0g 

"        two-cylinder   compound 171 

"           utility  of 275 

Rotative  effort,  diagrams  of 88,  93-94 


s. 

Saturation  curve , 50 


formula  for. . . 


303 

Saving  as  affected  by  price  of  fuel _, 258 

"         by  proper  operation  of  locomotives 264 

"  "         by  rate  of  combustion 258 

"     by  greater  expansion 254?  255 

"  more  complete   combustion 254,  256 

"  reduction  of  condensation 254 

"  reduction  of   radiation 256 

"       due  to  action  of  exhaust 136 

in  elevated  service 258 

"       in  fast  service 257 


INDEX. 

Saving  in  freight  service 257 

"       in. slow  service 257 

"       in  suburban  service 257 

"      of  compounds  in  U.  S 301,  302 

"      comparison  of  cost  of  repairs  to 264 

"       posibilities  of • 254 

"       reported  from  tests 254 

"       when  compounds   are  compared  with  over-worked  single  expansion  engines 260 

Saxon  State  R.  R.,  Lindner  starting  gear  on 185 

Schenectady    (Pitkin)    automatic   intercepting  valve 157 

"                   "                "                    "                 "       modification  of 160 

"                  "         two-cylinder  compound,  utility  of 275 

Selection  of  type  for  a  given  service 269 

Separate  exhaust  for  h.  p.  cylinder  and   intercepting  valve  (Colvin)  Pittsburgh  Locomotive 

Works 208 

"             "         for  h.  p.  cylinder,  Mallet  system 196 

"         for  h.  p.  cylinder  and  automatic  intercepting  valve  (Mellin) 205 

"         for  h.  p.  cylinder  and  intercepting  valve,  Rhode  Island  Locomotive  Works,  202 

"         for  h.  p.  cylinder  and  intercepting  valve,  von  Borries 209 

"         for  h.  p.  cylinder,  summary   about 251 

"         for  h.  p.  cylinder,  two -cylinder  receiver  compound 146 

Sequence  of  cranks 83 

Shop  tests 68,  255 

Single  expansion  locomotives,  starting  and  hauling  power  of 86 

Size  of  port  openings,  various  engines 111-121 

"         steam  passages i32 

Slide  valves,  proportion  of,  von  Borries 77,  7% 

Smoke  box  temperatures -  -  -  82 

Southern  Pacific  R.  R.,  independent  exhaust  for  h.  p.  cylinder  on 164 

Southwestern  Railway    of  Russia,  tandem  four-cylinder  on 237 

Speed,  high,  steam  distribution  at 267 

Starting  and  hauling  power  of  single  expansion  locomotives 86 

"         gear  and  cylinder  cocks,  recent  form  of  Vauclain 226 

"  «  "  "         Vauclain 217,222,224 

"             "         automatic,  with  intercepting  valves,  summary  about •. 249 

"             "         Cooke  Locomotive  Works i92 

"             "         for  four-cylinder  compounds,  summary  about 252 

"         Golsdorf  (Austrian) i94 

"             "         Lindner  automatic 181 

on  Saxon  State  R.  R 185 

"             "         modification  of  Lindner  automatic 184 

"             "         non- automatic,  summary   about 251 

"             "         summary  about 249 

"         of  four-cylinder  two-crank  receiver  and  non-receiver  compounds 85 

"         of  two-cylinder  receiver  compounds  with  independent  exhaust  for  h.  p.  cylinder 85 

«  "  "  without   an    independent    exhaust    for    h.   p. 

cylinder 84 

"         power,  Lindner  type 94 

"               "         of  four-cylinder  four-crank  compounds  with  receivers 86 

"               "         of  three -cylinder  three-crank  compounds 95 

Webb  type 95 

'•              "         with  automatic  gears 91 

"         with  Mallet's  system  and  other  non-automatic  starting  gears 90 

"         valve,  Brooks  Locomotive  Works  tandem  compound 243 

"     Mallet 197 

"         with  close-coupled  cars  and  free  slack 84 


INDEX.  327 


Steam  chest,  drop  in  pressure  between  boiler  and 133 

example  of  small  drop  in  pressure  between  boiler  and 133-4 

pressure,  drop  from  boiler 135 

"        variation  in T33>  136 

Steam,  condensed,  re-evaporation   of . . .  * 66 

"       distribution  at  high  speed 267 

"                 "           by  reverse  lever,  indicator  cards  showing 267 

"           in  three -cylinder  three-crank  types 284 

"           in  Vauclain  compound 220 

"           Vauclain  compound,  slow  speed 275 

"       jackets 80 

passages 132 

"         effect  on  expansion 255 

"         indicator  cards  showing  advantage  of   large  size  of 134 

"         re -evaporation  of  condensed  in  cylinders 52 

"         weight  of  at  different  points  of  the  stroke 101 ,  104 

"         weight  of  per  stroke , 51,  64 

for  various  compounds,  calculated  from  indicator  cards 66 

"         weight  of  retained  in  cylinder  at  end  of  compression 52 

"         weights,  curve   of  equal 50 

Stuffing-boxes,  h.  p.  and  1.  p.  combined  in  one 271 

Suburban  service,  mufflers  for  exhaust 136 

"                 "       saving    in 257 

Super-heat,  due  to  wire-drawing 132 

Super-heating  in  receiver 54 

T. 

Tandem,  Brooks  Locomotive  Works  starting  valve  for 243 

"     valve  arrangement 241 

"         compound,  Dunbar  four-cylinder  on  .Boston  &  Albany  R.  R 211 

"           four -cylinder,  on  Northern  Railway  of  France 211 

"         four-cylinder  on  Hungarian  State  Railways 235 

"                    "            on  Southwestern  Railway  of  Russia 237 

receiver   compounds 235 

"         indicator  cards  from  DuBousquet 213 

"         Mallet,  piston  for 237 

"         receiver  compounds,  starting  of 86 

Temperatures  of  smoke  boxes 82 

range  of,  in  cylinders 97 

Tests  in  shop 68,  255 

"       of  compounds  in  U.  S.  (Table) 301-302 

"       projected  Master  Mechanics  Association 255 

"       reported  savings 254 

Three  and  four-crank  compounds 244 

summary  about 248 

Three -cylinder  compound  on  Northern  Railways  of  France 246 

"                      "                            "                                "           valve  gear  for, 129 

Webb 244 

three-crank    types 284 

"  "     diagram  of  turning  moment 289-290 

"     distribution  of  work 288 

"                                            "     indicator  cards 285 

"     starting  power 95 

"     steam  distribution  in 284 

"                        "                  "     utility   of 270 


328 


INDEX. 


Three-cylinder  Webb,  express  compound 244 

"           freight          " 245 

"                 "           on  P.  R.  R 245 

Throttle,  effect  of  wire -drawing 264 

"        necessity  for  wide  open,  in  operating 131 

Total  cylinder  power,  per  cent,  of  consumed  by  locomotives  and  tenders 20 

"      expansion  from  actual  indicator  cards 69 

"            "               "     elementary   "           "      69 

Tractive  force,  formula  for 283 

"       power,  formula 86,  88 

Train  expenses  as  affected  by  price  of   fuel 258 

"             "         with  different  train  loads 260 

Travel  of  valve 122 

"  "     various  engines 111-121 

Turning  moment,  diagram  of,  Lindner  compound 299 

diagram  of,  three -cylinder,  three-crank  type 289-290 

"                                      two -cylinder  compounds,  Lindner 299 

Two-cylinder  compound,  Baldwin  Locomotive  Works 178 

"                    "            Brooks                                 "      169 

"                     "           Cooke                                  "      192 

"                     "           cylinder  capacity  compared  to  four-cylinder  compound 275 

"                     "                  "         ratio  of  Mallett  and  Brunner 78 

"           Dean 165 

"                     "           Gdlsdorf  (Austrian) 194 

"                    "            Lindner 181 

"                     "                  "         diagram  of  turning  moment 299 

"                     "                  "         on  C.,  B.  &  Q.,  design  of  Wm.  Forsyth 185 

"                    "                  '•         system,  P.  R.  R.,  design  of  Axel  S.  Vogt 188 

"                    "            Pitkin,  Schenectady  Locomotive  Works 157 

"                    "            Pittsburgh  Locomotive  Works  (Colvin)  system 208 

"                     "            (Player)  Brooks  Locomotive  Works 169 

'•                     "            Rhode  Island    Locomotive  Works  (Batchellor) 202 

"                     •'                        "                     "                 "          claims  for 205 

"                    "            Richmond                 "                 "           (Mellin) 205 

'•                     "            Rogers                       "                 "           171 

"                      "            ratio  of  cylinders  as  affecting  equalization  of  power  in 74 

"                     "            utility    of 275 

"                     "           valve  adjustment 276 

"  "  von  Borries i47>  209 

"  "  with    automatic   intercepting  valve    and   separate  exhaust  for  h. p. 

cylinder 146,  196 

"                                   with  independent  exhaust  for  h.  p.  cylinder,  starting  of 85 

"            without  independent  exhaust  for  h.  p.  cylinder,  starting  of 84 

valve  and     without   independent    exhaust   for 

h.  p.  cylinder 181 

Worsdell  type 153 

"             two-crank  receiver  types,  utility  of 275 

Types  of  compound  locomotives  commonly  used 2 


Valve  adjustment,  two-cylinder  compound 276 

"       arrangement,  Brooks   tandem 241 

"      for  h.  p.  cylinder,  C.  B.  &.  Q.  compound 188 

"      gear  adjustments 103 

"         "     for  three -cylinder  compound  on  Northern  Ry.  of  France 247 

"         "     proportions  of ,  tandem  compound 8 


INDEX.  329 

Valve  inside  lap  of 122 

"      motion,  as  affecting  compression 123 

"              "            wire-drawing 123 

"       conclusions  about  dimensions 130 

"              "                "        negative  lap , 130 

"            "             '"                "       valve  travel 131 

"       effect  of  Allan  port 131 

"       effect  of  increasing  outside  lap  on 124 

"             "              "            "            valve  travel 124 

"              "      inside  lap  and  negative  lap 124 

"      negative  lap  at  low  speeds 125,  127- 128 

"      on  expansion 255 

"             "      example  of  small  effect  of  negative  lap 129 

"            "      good-steam  distribution  in  single  expansion  locomotive 129 

"      large  negative  lap  on  P.  R.  R.  compound 130 

"      long  valve  travel  and  outside   lap  on  Philadelphia  &  Reading  R.  R 124,126 

"      meaning  of  term  as  here  used •  73 

"            "      some  effects  of  inadequate i 123 

"      negative  lap,  P.  R.  R..  two-cylinder  compound 191 

"      outside  lap  of 122 

"      P.  R.  R.  two-cylinder  compound 191 

"      various  engines 111-121 

"      piston 122 

"          "     bushing  for,  Vauclain  compound 217 

"           "     Vauclain 216 

"      slide,  proportions  of,  two- cylinder  compound,  von  Borries' 77,  78 

"      travel,  effect  of  increasing 124 

"        long  travel  and  wide  outside  lap  on  compression 121 

"  "       long,  and  outside   lap   on  Philadelphia  &  Reading  R.R. , 124,126 

"           "       of 122 

"          "      P.  R.R.  two-cylinder  compound 191 

"          "      valve  motions,  conclusions  about 131 

"          "      various  engines 111-121 

Variations  in  indicator  cards 35 

Vauclain  compound,  arrangement  of  crossheads  and  guides 218 

"                "           claims  for 232 

"           cylinders 216 

"           distribution  of  pressure  on  pistons 228 

"           inertia  of  reciprocating  parts  in 228 

"          steam  distribution  at  slow  speed 275 

"           utility  of 272 

";        crosshead 219 

"         four- cylinder  compounds,  Baldwin  Locomotive  Works 215 

"         piston  valves 216-217 

"           "       bushing 217 

"         starting  gear  and  cylinder  cocks 217,  222-224 

"           recent  form  of 226 

"         steam  distribution 220 

Vogt,  Axel  S.,  design  of  two-cylinder  compound  on  P.  R.R.,  Lindner  system 188 

von  Borries'  automatic  intercepting  valve 147 

"     early  form  of 149 

"     in  1889 147 

"     modification  of 152 

"»                                   "     on  Jura,  Berne -Lucerne 150 

"     recent  changes  in 153 

"              formula  for  proportions  of  cylinders 77 


33O  INDEX. 

von  Berries'  intercepting  valve  and  separate  exhaust  for  h.  p.  cylinder 209 

"               non- automatic  intercepting  valve 153 

"               rule  for  cylinder  ratios 73 

two-cylinder  compound *47>  209 

two- cylinder  compound,  utility  of 275 

type,  starting   power  of 71 

w. 

Webb  three-cylinder  compound 244 

; '                                 express  compound 244 

freight  compound 245 

"               "                on  P.  R.  R 245 

Weight  of  steam  different  points  of  the  stroke 101 ,  104 

"      per  stroke 51,  64,  101 

"           as  shown  by  indicator  cards 98 

"           for  various  compounds,   calculated  from  indicator  cards 66 

"      retained  in  cylinder  at  end  of  compression 52 

Western  Switzerland  R.  R.,  Mallet  system  on 196 

Wire-drawing  as  affected  by  driving  wheels 140 

"                         "                valve  motions 123 

"              at  high  speed 267 

effect  of,  on   economy 264 

"                      "        on    throttle 264 

"               loss  due  to ....  ~  ... 13 

super-heat  due  to 13 

Woolf  or  continuous  expansion   types 

type,  elementary  indicator  cards 

"                                                       "     four-cylinder : 21 

Work,  conclusions  about  equalization  in  h.  p.  and  1.  p.  cylinders 44 

"       difference  between  actual  and  that  shown  by  elementary  indicator  cards 31 

"       equalization  of,  in  h.  p.  and  1.  p.  cylinders  of  a  non-receiver  compound 43 

a  receiver  compound 42 

"       to  be  done,  ratio  of  cylinder  volumes  to 76 

Worsdell  automatic  intercepting  valve 153 

"     early  form  of 154 

"     modification   of 155 

"         two-cylinder  compound,  starting  power  of 91 

utility  of 275 

Worsdell  type  of  two-cylinder  compound 153 


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